Remove warnings about -g compiler flag

After strip there is no difference if -g is specified or not (as long
as the optimization level is set properly), so this warning was
spurious.

Author: chris-se

configure.ac

@@ -52,10 +52,6 @@ AS_CASE([$CFLAGS], [*-O[[12345\ ]]*],
         [AC_MSG_WARN([optimization level other than -Os specified in CFLAGS, this will increase your binary size.])], [])
 AS_CASE([$CFLAGS], [*-Os*],
         [], [AC_MSG_WARN([optimization level -Os not specified in CFLAGS, this will increase your binary size.])])
-AS_CASE([$CFLAGS], [*\ -g*],
-        [AC_MSG_WARN([debugging option -g specified in CFLAGS, this will increase your binary size.])], [])
-AS_CASE([$CFLAGS], [-g*],
-        [AC_MSG_WARN([debugging option -g specified in CFLAGS, this will increase your binary size.])], [])
 
 # Check if the user links against glibc.
 AC_COMPILE_IFELSE([AC_LANG_SOURCE([[#include <features.h>