configure.ac: enable some -Werror= warnings not included in -W -Wall -pedantic

For some reason, these warnings are not included in -W -Wall -pedantic, at least
not on gcc 14.2.1:

	-Wstrict-prototypes
	-Wmissing-prototypes
	-Wmissing-declarations

This caused a missing prototype error (because nasm_note[f]()
prototypes were missing from include/error.h) to get missed when
compiling with --enable-werror, which is ironic at best.

Signed-off-by: H. Peter Anvin <[email protected]>

Author: H. Peter Anvin

configure.ac

@@ -306,13 +306,17 @@ PA_ARG_ENABLED([werror],
   PA_ADD_CFLAGS([-Werror=return-type])
   PA_ADD_CFLAGS([-Werror=trigraphs])
   PA_ADD_CFLAGS([-Werror=pointer-arith])
-  PA_ADD_CFLAGS([-Werror=strict-prototypes])
-  PA_ADD_CFLAGS([-Werror=missing-prototypes])
-  PA_ADD_CFLAGS([-Werror=missing-declarations])
   PA_ADD_CFLAGS([-Werror=comment])
   PA_ADD_CFLAGS([-Werror=vla])]
 )
 
+dnl These warnings are apparently not included in -Wall -W -pedantic
+dnl for some bizarre reason. They are, however, absolutely forbidden
+dnl in this code base.
+PA_ADD_CFLAGS([-Werror=strict-prototypes])
+PA_ADD_CFLAGS([-Werror=missing-prototypes])
+PA_ADD_CFLAGS([-Werror=missing-declarations])
+
 dnl Variadic macros are used in this code, but only under explicit guard
 PA_ADD_CFLAGS([-Wvariadic-macros],[-Wno-variadic-macros])
 dnl Suppress format warning on Windows targets due to their <inttypes.h>