Fixed some wrong usage of my_bool

Fixed compiler warning
Ensure that pagecache returns correct error number


storage/maria/ma_pagecache.c:
  Ensure that block->error contain error code from my_errno (not return value from pread/pwrite)
  Went through usage of my_pread/my_pwrite and ensured that result was threated correctly
  Fixed some wrong usage of my_bool

storage/maria/ma_pagecache.c

@@ -593,10 +593,10 @@ extern my_bool translog_flush(TRANSLOG_ADDRESS lsn);
 
   RETURN
     0   - OK
-    !=0 - Error
+    1   - Error
 */
 
-static uint pagecache_fwrite(PAGECACHE *pagecache,
+static my_bool pagecache_fwrite(PAGECACHE *pagecache,
                                 PAGECACHE_FILE *filedesc,
                                 uchar *buffer,
                                 pgcache_page_no_t pageno,
@@ -2069,7 +2069,7 @@ restart:
                             (my_bool)(block->hash_link ? 1 : 0));
           PCBLOCK_INFO(block);
           block->status= error ? PCBLOCK_ERROR : 0;
-          block->error=  error;
+          block->error=  (int16) my_errno;
 #ifndef DBUG_OFF
           block->type= PAGECACHE_EMPTY_PAGE;
           if (error)
@@ -2608,7 +2608,7 @@ static void read_block(PAGECACHE *pagecache,
     if (error)
     {
       block->status|= PCBLOCK_ERROR;
-      block->error=   error;
+      block->error=   (int16) my_errno;
       my_debug_put_break_here();
     }
     else
@@ -2621,7 +2621,7 @@ static void read_block(PAGECACHE *pagecache,
       {
         DBUG_PRINT("error", ("read callback problem"));
         block->status|= PCBLOCK_ERROR;
-        block->error=  my_errno;
+        block->error=  (int16) my_errno;
         my_debug_put_break_here();
       }
     }
@@ -3111,7 +3111,7 @@ uchar *pagecache_read(PAGECACHE *pagecache,
                       enum pagecache_page_lock lock,
                       PAGECACHE_BLOCK_LINK **page_link)
 {
-  int error= 0;
+  my_bool error= 0;
   enum pagecache_page_pin pin= lock_to_pin[test(buff==0)][lock];
   PAGECACHE_BLOCK_LINK *fake_link;
   my_bool reg_request;
@@ -3292,7 +3292,7 @@ static my_bool pagecache_delete_internal(PAGECACHE *pagecache,
                                          PAGECACHE_HASH_LINK *page_link,
                                          my_bool flush)
 {
-  int error= 0;
+  my_bool error= 0;
   if (block->status & PCBLOCK_CHANGED)
   {
     if (flush)
@@ -3319,7 +3319,7 @@ static my_bool pagecache_delete_internal(PAGECACHE *pagecache,
       if (error)
       {
         block->status|= PCBLOCK_ERROR;
-        block->error=   error;
+        block->error=   (int16) my_errno;
         my_debug_put_break_here();
         goto err;
       }
@@ -3368,7 +3368,7 @@ my_bool pagecache_delete_by_link(PAGECACHE *pagecache,
                                  enum pagecache_page_lock lock,
                                  my_bool flush)
 {
-  int error= 0;
+  my_bool error= 0;
   enum pagecache_page_pin pin= PAGECACHE_PIN_LEFT_PINNED;
   DBUG_ENTER("pagecache_delete_by_link");
   DBUG_PRINT("enter", ("fd: %d block 0x%lx  %s  %s",
@@ -3467,7 +3467,7 @@ my_bool pagecache_delete(PAGECACHE *pagecache,
                          enum pagecache_page_lock lock,
                          my_bool flush)
 {
-  int error= 0;
+  my_bool error= 0;
   enum pagecache_page_pin pin= lock_to_pin[0][lock];
   DBUG_ENTER("pagecache_delete");
   DBUG_PRINT("enter", ("fd: %u  page: %lu  %s  %s",
@@ -3655,7 +3655,7 @@ my_bool pagecache_write_part(PAGECACHE *pagecache,
 {
   PAGECACHE_BLOCK_LINK *block= NULL;
   PAGECACHE_BLOCK_LINK *fake_link;
-  int error= 0;
+  my_bool error= 0;
   int need_lock_change= write_lock_change_table[lock].need_lock_change;
   my_bool reg_request;
 #ifndef DBUG_OFF
@@ -3778,7 +3778,7 @@ restart:
         {
           DBUG_PRINT("error", ("read callback problem"));
           block->status|= PCBLOCK_ERROR;
-          block->error= my_errno;
+          block->error= (int16) my_errno;
           my_debug_put_break_here();
         }
         KEYCACHE_DBUG_PRINT("key_cache_insert",
@@ -3868,10 +3868,10 @@ no_key_cache:
       uchar *page_buffer= (uchar *) alloca(pagecache->block_size);
 
       pagecache->global_cache_read++;
-      if ((error= pagecache_fread(pagecache, file,
+      if ((error= (pagecache_fread(pagecache, file,
                                    page_buffer,
                                    pageno,
-                                  pagecache->readwrite_flags)))
+                                   pagecache->readwrite_flags) != 0)))
         goto end;
       if ((file->read_callback)(page_buffer, pageno, file->callback_data))
       {
@@ -3995,7 +3995,7 @@ static int flush_cached_blocks(PAGECACHE *pagecache,
                                int *first_errno)
 {
   int rc= PCFLUSH_OK;
-  int error;
+  my_bool error;
   uint count= (uint) (end-cache);
   DBUG_ENTER("flush_cached_blocks");
   *first_errno= 0;
@@ -4075,7 +4075,7 @@ static int flush_cached_blocks(PAGECACHE *pagecache,
     if (error)
     {
       block->status|= PCBLOCK_ERROR;
-      block->error=   error;
+      block->error=   (int16) my_errno;
       my_debug_put_break_here();
       if (!*first_errno)
         *first_errno= my_errno ? my_errno : -1;