message: cxx: fix the computation of the default C compiler
  clang++-mp-3.9 gave gcc-3.9, instead of clang-mp-3.9.
diff: @@ -643,7 +643,12 @@ class GccToolkit(Toolkit):
  self.__version = tuple(map(int, self.preprocess_values(vars)))
  else:
  raise Exception('unknown GCC kind')
  - self.c = compiler_c or '%sgcc%s' % (self.prefix, self.suffix)
  + self.c = compiler_c or '%s%s%s' % (self.prefix,
  + self.basename
  + # Order matters.
  + .replace('clang++', 'clang')
  + .replace('g++', 'gcc'),
  + self.suffix)
  if archiver:
  self.ar = archiver
  else:
  @@ -1020,7 +1025,7 @@ class GccToolkit(Toolkit):
  if self.__splitted is None:
  # On MacPorts, compilers are named clang++-mp-3.9, g++-mp-6, etc.
  r = re.compile(
  - '(.*-)?(g\+\+|clang\+\+)(?:-mp)?(-[0-9]+(\.[0-9]+(\.[0-9]+)?)?)?$')
  + '(.*-)?(g\+\+|clang\+\+)((?:-mp)?-[0-9]+(\.[0-9]+(\.[0-9]+)?)?)?$')
  match = r.match(self.cxx)
  if not match:
  raise Exception('unrecognized compiler name: %s' % self.cxx)
  @@ -1029,10 +1034,17 @@ class GccToolkit(Toolkit):
  @property
  def prefix(self):
  + '''The prefix to the compiler name, e.g., `arm-`.'''
  return self.__split()[0]
  + @property
  + def basename(self):
  + '''The compiler basename, e.g., `clang++`.'''
  + return self.__split()[1]
  +
  @property
  def suffix(self):
  + '''The compiler suffix, e.g., `-mp-3.9`.'''
  return self.__split()[2]
  @property
  