Fixed a few improper macro usages

Added compiler checks for some improper macro usage and fixed the problems
pointed by gcc.

Signed-off-by: Christophe CURIS <christophe.curis@free.fr>

WINGs/string.c

@@ -242,7 +242,7 @@ char *wstrappend(char *dst, const char *src)
 }
 
 
-#if HAVE_STRLCAT
+#ifdef HAVE_STRLCAT
 size_t
 wstrlcat(char *dst, const char *src, size_t siz)
 {
@@ -303,7 +303,7 @@ wstrlcat(char *dst, const char *src, size_t siz)
 }
 #endif /* HAVE_STRLCAT */
 
-#if HAVE_STRLCPY
+#ifdef HAVE_STRLCPY
 size_t
 wstrlcpy(char *dst, const char *src, size_t siz)
 {

configure.ac

@@ -143,6 +143,10 @@ AS_IF([test "x$debug" = "xyes"],
      dnl secured OS, and in a more general way generate binary code
      dnl that may not be optimal
      AX_CFLAGS_GCC_OPTION([-Wtrampolines])
+     dnl
+     dnl GCC provides a couple of checks to detect incorrect macro uses
+     AX_CFLAGS_GCC_OPTION([-Wundef])
+     AX_CFLAGS_GCC_OPTION([-Wunused-macros])
 ], [dnl
      dnl When debug not enabled, we try to avoid some non-necessary
      dnl messages from the compiler

util/wmgenmenu.c

@@ -71,7 +71,7 @@ int main(int argc, char *argv[])
 	path = getenv("PATH");
 	setlocale(LC_ALL, "");
 
-#if HAVE_LIBINTL_H && I18N
+#if defined(HAVE_LIBINTL_H) && defined(I18N)
 	if (getenv("NLSPATH"))
 		bindtextdomain("wmgenmenu", getenv("NLSPATH"));
 	else