[gnome-screenshot] build: Define both _POSIX_C_SOURCE and _XOPEN_SOURCE with versions

[Ting-Wei Lan <lantw src gnome org>]

commit 1089e4cca5c3f82b6088dc945eef9badfefff149
Author: Ting-Wei Lan <lantw src gnome org>
Date:   Tue Jun 6 00:10:06 2017 +0800

    build: Define both _POSIX_C_SOURCE and _XOPEN_SOURCE with versions
    
    FreeBSD libc assumes defining _POSIX_C_SOURCE without specifying a
    version means a pre-C89 environment with the oldest version of POSIX
    standard, IEEE Std 1003.1-1988. Defining _POSIX_C_SOURCE without
    defining _XOPEN_SOURCE also causes XSI to be disabled. However, M_PI
    constant is only available in XSI. Therefore, we have to define
    _XOPEN_SOURCE if we want to define _POSIX_C_SOURCE.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=783442

 meson.build |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/meson.build b/meson.build
index 66bb84c..7927cb0 100644
--- a/meson.build
+++ b/meson.build
@@ -8,7 +8,7 @@ project('gnome-screenshot', 'c',
           'c_std=c99',
         ])
 
-add_project_arguments([ '-D_POSIX_C_SOURCE', '-D_DEFAULT_SOURCE' ], language: 'c')
+add_project_arguments([ '-D_POSIX_C_SOURCE=200809L', '-D_XOPEN_SOURCE=700', '-D_DEFAULT_SOURCE' ], language: 
'c')
 
 cc = meson.get_compiler('c')