Remove support for MetroWerks CodeWarrior compiler.

This compiler doesn't exist any more and was probably unsupported even in 2.8,
let alone 2.9, so remove all the __MWERKS__ tests to simplify things.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@71102 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/osx/carbon/graphics.cpp

@@ -113,11 +113,9 @@ extern "C"
 // constants
 //-----------------------------------------------------------------------------
 
-#if !defined( __DARWIN__ ) || defined(__MWERKS__)
 #ifndef M_PI
 const double M_PI = 3.14159265358979;
 #endif
-#endif
 
 static const double RAD2DEG = 180.0 / M_PI;