Change mysqld_safe search for mysqld relative to the current working directory

to only look for the mysqld binary (and english error strings) and assume the
datadir from that. Then, if that datadir turns out to not exist, startup will
fail. This avoids the behavior where mysqld_safe would go off and run a totally
different binary because the data directory had been moved (even when --datadir
was specified on the command line). (Bug #7249)


scripts/mysqld_safe.sh:
  Don't actually verify that datadir exists when
  using relatively-located mysqld -- just assume
  that it does and either let it fail when it
  doesn't, or do the right thing when datadir
  is then set via the command line or my.cnf file.

scripts/mysqld_safe.sh

@@ -86,7 +86,7 @@ parse_arguments() {
 
 MY_PWD=`pwd`
 # Check if we are starting this relative (for the binary release)
-if test -d $MY_PWD/data/mysql -a -f ./share/mysql/english/errmsg.sys -a \
+if test -f ./share/mysql/english/errmsg.sys -a \
  -x ./bin/mysqld
 then
   MY_BASEDIR_VERSION=$MY_PWD		# Where bin, share and data are
@@ -97,7 +97,7 @@ then
     defaults="--defaults-extra-file=$MY_BASEDIR_VERSION/data/my.cnf"
   fi
 # Check if this is a 'moved install directory'
-elif test -f ./var/mysql/db.frm -a -f ./share/mysql/english/errmsg.sys -a \
+elif test -f ./share/mysql/english/errmsg.sys -a \
  -x ./libexec/mysqld
 then
   MY_BASEDIR_VERSION=$MY_PWD		# Where libexec, share and var are