Bug 1186784 - Disable snprintf definition in libav on VC2015. r=glandium

--HG--
extra : source : 03d4ebfe2c987137c006e18ca7787d246d3826a9

media/libav/libavcommon.mozbuild

@@ -12,8 +12,9 @@ if CONFIG['OS_ARCH'] == 'WINNT':
     # Fix inline symbols and math defines for windows.
     DEFINES['_USE_MATH_DEFINES'] = True
     DEFINES['inline'] = "__inline"
-    # snprintf is prefixed with an underscore on windows.
-    DEFINES['snprintf'] = "_snprintf"
+    if CONFIG['_MSC_VER'] and CONFIG['_MSC_VER'] < 1900:
+        # snprintf is prefixed with an underscore on MSVC 2013.
+        DEFINES['snprintf'] = "_snprintf"
     ASFLAGS += ['-Pconfig_win.asm']
     # 32-bit windows need to prefix symbols with an underscore.
     if CONFIG['CPU_ARCH'] == 'x86':