Update limits headers for better platform compat

This change enables building libcper based cli tools on mac systems.

Change-Id: If9b0134d3677b84c57603fa83d546b58e8c2d073
Signed-off-by: Andrew Adriance <aadriance@nvidia.com>
diff --git a/cli-app/cper-convert.c b/cli-app/cper-convert.c
index 0ebc707..5ff748b 100644
--- a/cli-app/cper-convert.c
+++ b/cli-app/cper-convert.c
@@ -8,7 +8,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <libgen.h>
-#include <linux/limits.h>
+#include <limits.h>
 #include <json.h>
 #include "../cper-parse.h"
 #include "../json-schema.h"
diff --git a/json-schema.c b/json-schema.c
index 8000bda..9c0ed36 100644
--- a/json-schema.c
+++ b/json-schema.c
@@ -14,7 +14,6 @@
 #include <json.h>
 #include "json-schema.h"
 #include "edk/BaseTypes.h"
-#include <linux/limits.h>
 
 //Field definitions.
 int json_validator_debug = 0;
diff --git a/meson.build b/meson.build
index 04b8094..624d85b 100644
--- a/meson.build
+++ b/meson.build
@@ -20,6 +20,7 @@
 )
 
 library_is_share = get_option('default_library') == 'shared'
+add_global_arguments('-D_POSIX_C_SOURCE=200809L', language : 'c')
 
 project_description = 'libcper library'