Enable full GCC compiler warnings by default

git-svn-id: svn+ssh://svn.code.sf.net/p/libjpeg-turbo/code/trunk@462 632fc199-4ca6-4c93-a231-07263d6284db

configure.ac

@@ -13,6 +13,7 @@ AC_DEFINE([HAVE_PROTOTYPES], 1, [Define if your compiler supports prototypes])
 
 # Checks for programs.
 SAVED_CFLAGS=${CFLAGS}
+SAVED_CPPFLAGS=${CPPFLAGS}
 AC_PROG_CPP
 AC_PROG_CC
 AC_PROG_INSTALL
@@ -30,6 +31,9 @@ if test "x${GCC}" = "xyes"; then
   if test "x${SAVED_CFLAGS}" = "x"; then
     CFLAGS=-O3
   fi
+  if test "x${SAVED_CPPFLAGS}" = "x"; then
+    CPPFLAGS=-Wall
+  fi
 fi
 
 AC_CHECK_DECL([__SUNPRO_C], [SUNCC="yes"], [SUNCC="no"])