Add a fallback for missing stdbool.h

Older versions of the Microsoft Visual C compiler do not support C99 and
do not have stdbool.h.

Additionally, Epoxy is pretty much C89 compliant, and stdbool.h is part
of C99.

We can add a simple fallback for MSVC, in case we end up getting built
with it.

include/epoxy/common.h

@@ -41,4 +41,12 @@
 # define EPOXY_PUBLIC extern
 #endif
 
+#if defined(_MSC_VER) && !defined(__bool_true_false_are_defined) && (_MSC_VER < 1800)
+typedef unsigned char bool;
+# define false 0
+# define true 1
+#else
+# include <stdbool.h>
+#endif
+
 #endif /* EPOXY_COMMON_H */

include/epoxy/egl.h

@@ -30,8 +30,6 @@
 #ifndef EPOXY_EGL_H
 #define EPOXY_EGL_H
 
-#include <stdbool.h>
-
 #include "epoxy/common.h"
 
 #if defined(__egl_h_) || defined(__eglext_h_)

include/epoxy/gl.h

@@ -30,8 +30,6 @@
 #ifndef EPOXY_GL_H
 #define EPOXY_GL_H
 
-#include <stdbool.h>
-
 #include "epoxy/common.h"
 
 #if defined(__gl_h_) || defined(__glext_h_)

include/epoxy/glx.h

@@ -33,7 +33,6 @@
 #include <epoxy/gl.h>
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
-#include <stdbool.h>
 
 #if defined(GLX_H) || defined(__glxext_h_)
 #error epoxy/glx.h must be included before (or in place of) GL/glx.h

include/epoxy/wgl.h

@@ -30,7 +30,6 @@
 #ifndef EPOXY_WGL_H
 #define EPOXY_WGL_H
 
-#include <stdbool.h>
 #include <windows.h>
 
 #include "epoxy/common.h"