Fix negative font rendering on Mac by reversing matrix c component.

core/fxge/apple/fx_apple_platform.cpp

Index: core/fxge/apple/fx_apple_platform.cpp
diff --git a/core/fxge/apple/fx_apple_platform.cpp b/core/fxge/apple/fx_apple_platform.cpp
index 2108d4d2e46432124cec8d62e48a9692d1b40261..211e5745e21b787c15bb9b9a140142d6f3655e33 100644
--- a/core/fxge/apple/fx_apple_platform.cpp
+++ b/core/fxge/apple/fx_apple_platform.cpp
@@ -72,6 +72,7 @@ FX_BOOL CGDrawGlyphRun(CGContextRef pContext,
   }
   if (bNegSize) {
     new_matrix.a = -new_matrix.a;
+    new_matrix.c = -new_matrix.c;
   } else {
     new_matrix.b = -new_matrix.b;
     new_matrix.d = -new_matrix.d;