cleanup scons build flags, many duplicates because because of confusion between CFLAGS/CPPFLAGS/CCFLAGS/CXXFLAGS, devs would set multiple to be on the safe side.

- defines go in CPPFLAGS
- C & C++ flags go in CCFLAGS
- CFLAGS / CXXFLAGS are C OR C++ only.

also commented intended ghost unicode/ascii usage.

build_files/scons/config/linux-config.py

@@ -199,15 +199,16 @@ CXX = 'g++'
 ##   CFLAGS += -pipe -fPIC -funsigned-char -fno-strict-aliasing -mieee
 
 CCFLAGS = ['-pipe','-fPIC','-funsigned-char','-fno-strict-aliasing','-D_LARGEFILE_SOURCE', '-D_FILE_OFFSET_BITS=64','-D_LARGEFILE64_SOURCE']
+CXXFLAGS = []
 
 CPPFLAGS = []
-CXXFLAGS = ['-pipe','-fPIC','-funsigned-char','-fno-strict-aliasing','-D_LARGEFILE_SOURCE', '-D_FILE_OFFSET_BITS=64','-D_LARGEFILE64_SOURCE']
 # g++ 4.6, only needed for bullet
 CXXFLAGS += ['-fpermissive']
 if WITH_BF_FFMPEG:
   # libavutil needs UINT64_C()
   CXXFLAGS += ['-D__STDC_CONSTANT_MACROS', ]
-REL_CFLAGS = ['-DNDEBUG', '-O2']
+REL_CFLAGS = []
+REL_CXXFLAGS = []
 REL_CCFLAGS = ['-DNDEBUG', '-O2']
 ##BF_DEPEND = True
 ##