gallium: Provide alternative stdint.h and stdbool.h C99 headers, instead of ad-hoc definitions.

Everybody is using the C99's integer types. Everybody except Microsoft,
which in turns means everybody is including their own definitions of C99
integer types for MSVC, causing duplicate definitions when linking two
projects. This is the case of building Gallium and LLVM with MSVC.

Shipping alternative stdint.h and stdbool.h headers for MSVC allows us
to share a single definition. It also removes clutter from the Gallium
headers.

src/gallium/include/pipe/p_compiler.h

@@ -52,45 +52,15 @@
 #endif /* _MSC_VER */
 
 
-#if defined(_MSC_VER)
-
-typedef __int8             int8_t;
-typedef unsigned __int8    uint8_t;
-typedef __int16            int16_t;
-typedef unsigned __int16   uint16_t;
-#ifndef __eglplatform_h_
-typedef __int32            int32_t;
-#endif
-typedef unsigned __int32   uint32_t;
-typedef __int64            int64_t;
-typedef unsigned __int64   uint64_t;
-
-#if defined(_WIN64)
-typedef __int64            intptr_t;
-typedef unsigned __int64   uintptr_t;
-#else
-typedef __int32            intptr_t;
-typedef unsigned __int32   uintptr_t;
-#endif
-
-#define INT64_C(__val) __val##i64
-#define UINT64_C(__val) __val##ui64
-
-#ifndef __cplusplus
-#define false   0
-#define true    1
-#define bool    _Bool
-typedef int     _Bool;
-#define __bool_true_false_are_defined   1
-#endif /* !__cplusplus */
-
-#else
+/*
+ * Alternative stdint.h and stdbool.h headers are supplied in include/c99 for
+ * systems that lack it.
+ */
 #ifndef __STDC_LIMIT_MACROS
 #define __STDC_LIMIT_MACROS 1
 #endif
 #include <stdint.h>
 #include <stdbool.h>
-#endif
 
 
 #ifndef __HAIKU__