Undefine 'near' and 'far' in mat4.h for host Windows

Previously, when a C++ file included 'windows.h' and subsequently
included 'mat4.h', a compile error occurred. This is because, for some
esoteric/obsolete reasons, 'windows.h' includes empty definitions of
'near' and 'far'. These conflict with the usage of 'near' and 'far' in
'mat4.h'.

Add some logic to 'mat4.h' for host Windows that undefines 'near' and
'far' to avoid these conflicts.

Test: Build libandroid_runtime on Windows
Bug: 328307399
Change-Id: I13d068e7f800cf370a0f7d9f1b98479f9c6aeb35

Author: hoisie

libs/math/include/math/mat4.h

@@ -34,6 +34,14 @@
 #define CONSTEXPR
 #endif
 
+#ifdef _WIN32
+// windows.h contains obsolete defines of 'near' and 'far' for systems using
+// legacy 16 bit pointers. Undefine them to avoid conflicting with the usage of
+// 'near' and 'far' in this file.
+#undef near
+#undef far
+#endif
+
 namespace android {
 // -------------------------------------------------------------------------------------
 namespace details {