mesa compile fixes for Clang / VS2013

src/mesa/main/imports.h

Index: src/mesa/main/imports.h
diff --git a/src/mesa/main/imports.h b/src/mesa/main/imports.h
index 4b74f70d338a3aeef2c099b6b4574c59c93944d8..827db2e5eba86d0e569fa9b2b1c799287d11b8ce 100644
--- a/src/mesa/main/imports.h
+++ b/src/mesa/main/imports.h
@@ -145,6 +145,7 @@ typedef union { GLfloat f; GLint i; GLuint u; } fi_type;
 #endif
 
 #if defined(_MSC_VER)
+#if _MSC_VER < 1800  /* Not required on VS2013 and above. */
 static inline float truncf(float x) { return x < 0.0f ? ceilf(x) : floorf(x); }
 static inline float exp2f(float x) { return powf(2.0f, x); }
 static inline float log2f(float x) { return logf(x) * 1.442695041f; }
@@ -153,6 +154,7 @@ static inline float acoshf(float x) { return logf(x + sqrtf(x * x - 1.0f)); }
 static inline float atanhf(float x) { return (logf(1.0f + x) - logf(1.0f - x)) / 2.0f; }
 static inline int isblank(int ch) { return ch == ' ' || ch == '\t'; }
 #define strtoll(p, e, b) _strtoi64(p, e, b)
+#endif  /* _MSC_VER < 1800 */
 #endif
 /*@}*/