win-capture: Use inline define with VC only

mingw already supports the regular inline keyword in C; VC does not.

plugins/win-capture/funchook.h

@@ -6,7 +6,7 @@
 #ifdef __cplusplus
 extern "C" {
 #else
-#ifndef inline
+#if defined(_MSC_VER) && !defined(inline)
 #define inline __inline
 #endif
 #endif

plugins/win-capture/get-graphics-offsets/get-graphics-offsets.h

@@ -9,7 +9,7 @@
 #ifdef __cplusplus
 extern "C" {
 #else
-#ifndef inline
+#if defined(_MSC_VER) && !defined(inline)
 #define inline __inline
 #endif
 #endif

plugins/win-capture/graphics-hook/graphics-hook.h

@@ -11,7 +11,7 @@
 #ifdef __cplusplus
 extern "C" {
 #else
-#ifndef inline
+#if defined(_MSC_VER) && !defined(inline)
 #define inline __inline
 #endif
 #endif