Improved detection of mprotect()

configure.in

@@ -146,7 +146,16 @@ if test x$enable_libc = xyes; then
     if test x$ac_cv_func_strtod = xyes; then
         AC_DEFINE(HAVE_STRTOD)
     fi
-    AC_CHECK_FUNCS(malloc calloc realloc free getenv putenv unsetenv qsort abs bcopy memset memcpy memmove strlen strlcpy strlcat strdup _strrev _strupr _strlwr strchr strrchr strstr itoa _ltoa _uitoa _ultoa strtol strtoul _i64toa _ui64toa strtoll strtoull atoi atof strcmp strncmp _stricmp strcasecmp _strnicmp strncasecmp sscanf snprintf vsnprintf iconv sigaction setjmp nanosleep mprotect)
+    AC_CHECK_FUNC(mprotect,
+        AC_TRY_COMPILE([
+          #include <sys/types.h>
+          #include <sys/mman.h>
+        ],[
+        ],[
+        AC_DEFINE(HAVE_MPROTECT)
+        ]),
+    )
+    AC_CHECK_FUNCS(malloc calloc realloc free getenv putenv unsetenv qsort abs bcopy memset memcpy memmove strlen strlcpy strlcat strdup _strrev _strupr _strlwr strchr strrchr strstr itoa _ltoa _uitoa _ultoa strtol strtoul _i64toa _ui64toa strtoll strtoull atoi atof strcmp strncmp _stricmp strcasecmp _strnicmp strncasecmp sscanf snprintf vsnprintf iconv sigaction setjmp nanosleep)
 
     AC_CHECK_LIB(iconv, libiconv_open, [EXTRA_LDFLAGS="$EXTRA_LDFLAGS -liconv"])
     AC_CHECK_LIB(m, pow, [EXTRA_LDFLAGS="$EXTRA_LDFLAGS -lm"])