Fix gcc2 build on Mac OS X Lion.

The gcc2 cross-compiler built on Mac OS X Lion has a bug in it
where it is erroring with 'cast specifies signature type' when
assigning 0 or NULL to a pointer to a member fuction. NULL in this
instance is correctly converted to 0 since it is illegal to assign
((void*)0) to a pointer to a member function. However, it should
be legal to assign 0 to a pointer to a member function. Thus, there
is a bug.  Since I can't fix the gcc2 compiler I am working around
this bug by assigning the pointer to a do nothing function instead.

My host compiler version is
i686-apple-darwin11-gcc-4.2.1 (GCC) 4.2.1 (Apple Inc. build 5666) (dot 3)

The same error occurs using the default gcc-llvm compiler and
a standard gcc 4.61 built from source. This bug does not occur on
Mac OS X 10.6 gcc2 or gcc4, nor does it occur on Mac OS X 10.7 with
the gcc4 cross-compiler.

If and when we decide to finally leave gcc2 behind we can revert this
change.

headers/libs/print/libprint/Halftone.h

@@ -102,6 +102,14 @@ protected:
 			void		SetupErrorBuffer(int x, int y, int width);
 			void		DitherFloydSteinberg(uchar* destination,
 							const uchar* source, int x, int y, int width);
+						// Do nothing method to get around a bug in
+						// the gcc2 cross-compiler built on Mac OS X
+						// Lion where a compiler error occurs when
+						// assigning a member function pointer to NULL
+						// or 0: cast specifies signature type.
+						// However, this should be legal according to
+						// the C++03 standard.
+			void		DitherNone(uchar*, const uchar*, int, int, int) {};
 
 private:
 	enum {

src/add-ons/media/media-add-ons/mixer/Resampler.cpp

@@ -21,7 +21,7 @@
 
 Resampler::Resampler(uint32 src_format, uint32 dst_format)
 	:
-	fFunc(0)
+	fFunc(&Resampler::no_conversion)
 {
 	if (dst_format == media_raw_audio_format::B_AUDIO_FLOAT) {
 		switch (src_format) {
@@ -81,7 +81,7 @@ Resampler::~Resampler()
 status_t
 Resampler::InitCheck() const
 {
-	return fFunc != 0 ? B_OK : B_ERROR;
+	return fFunc != &Resampler::no_conversion ? B_OK : B_ERROR;
 }
 
 

src/add-ons/media/media-add-ons/mixer/Resampler.h

@@ -65,6 +65,15 @@ private:
 									int32 srcSampleOffset, int32 srcSampleCount,
 									void* dest, int32 destSampleOffset,
 									int32 destSampleCount, float gain);
+								// Do nothing method to get around a bug in
+								// the gcc2 cross-compiler built on Mac OS X
+								// Lion where a compiler error occurs when
+								// assigning a member function pointer to NULL
+								// or 0: cast specifies signature type.
+								// However, this should be legal according to
+								// the C++03 standard.
+			void				no_conversion(const void*, int32, int32, void*,
+									int32, int32, float) {};
 };
 
 

src/libs/print/libprint/Halftone.cpp

@@ -84,7 +84,7 @@ Halftone::Halftone(color_space colorSpace, double gamma, double min,
 			fDither = &Halftone::DitherRGB32;
 			break;
 		default:
-		fDither = NULL;
+			fDither = &Halftone::DitherNone;
 			break;
 	}
 }
@@ -364,4 +364,3 @@ Halftone::DitherFloydSteinberg(uchar *destination, const uchar* source0,
 		*destination = ConvertUsingBlackValue(cur);
 	}
 }
-