Remove the DONT_CLOBBER_CC option, don't clobber CC, and detect the name

of the compiler (icc, gcc, and clang supported).

src/build/Common.gmake

@@ -57,7 +57,6 @@
 #						is cleared)											#
 #  USE_UPROFILE		- Builds using information generated by UPROFILE.		#
 #					  (RELEASE builds only)									#
-#  DONT_CLOBBER_CC	- Do not change the default setting of CC				#
 #  OBJPATH_SUFFIX	- Suffix appended to OBJPATH useful for compiling 		#
 #					  different options of the same source file				#
 #  STATIC			- Create a statically linked build if possible			#
@@ -157,13 +156,9 @@ endif
 
 # Compiler-specific options
 CFLAGS	+=	-MMD
-ifdef BUILD_DEPENDS
- ifdef DONT_CLOBBER_CC
 CC		?=	gcc
- else
-  CC			:=	gcc
- endif
- CCPRE			:=	$(CC)
+CCPRE	?= ${shell if [ `echo __clang__ | $(CC) -E - | grep -v '^\#'` != __clang__ ] ; then echo clang ; elif [`echo __INTEL_COMPILER | $(CC) -E - | grep -v '^\#'` != __INTEL_COMPILER ] ; then echo icc ; else echo gcc ; fi}
+ifdef BUILD_DEPENDS
  CC				:=	$(SRC_ROOT)/build/mkdep -a
  CXX			:=	$(SRC_ROOT)/build/mkdep -a
  LD				:=	echo
@@ -171,12 +166,6 @@ ifdef BUILD_DEPENDS
  AR				:=	echo
  RANLIB			:=	echo
 else
- ifdef DONT_CLOBBER_CC
-  CC			?=	gcc
- else
-  CC			:=	gcc
- endif
- CCPRE			:=	$(CC)
  CXX			?=	g++
  LD				?=	ld
  COMPILE_MSG	:= Compiling