um: don't export printf()

Since printf() cannot be used in kernel threads (it
uses too much stack space) don't export it for modules
either.

This should leave us exporting only things that are
absolutely critical (such as memset and friends) and
things that are injected by the compiler (stack guard
and similar.)
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Richard Weinberger <richard@nod.at>

arch/um/os-Linux/user_syms.c

@@ -18,7 +18,6 @@
 extern size_t strlen(const char *);
 extern void *memmove(void *, const void *, size_t);
 extern void *memset(void *, int, size_t);
-extern int printf(const char *, ...);
 
 /* If it's not defined, the export is included in lib/string.c.*/
 #ifdef __HAVE_ARCH_STRSTR
@@ -32,8 +31,6 @@ EXPORT_SYMBOL(memmove);
 EXPORT_SYMBOL(memset);
 #endif
 
-EXPORT_SYMBOL(printf);
-
 #ifdef CONFIG_ARCH_REUSE_HOST_VSYSCALL_AREA
 EXPORT_SYMBOL(vsyscall_ehdr);
 EXPORT_SYMBOL(vsyscall_end);