From: Helmut Grohne <helmut@subdivi.de>
Subject: have tbb honour $(CC) and $(CXX)

--- a/build/FreeBSD.gcc.inc
+++ b/build/FreeBSD.gcc.inc
@@ -24,8 +24,8 @@
 DYLIB_KEY = -shared
 WARNING_SUPPRESS = -Wno-parentheses
 
-CPLUS = g++ 
-CONLY = gcc
+CPLUS = $(CXX)
+CONLY = $(CC)
 LIB_LINK_FLAGS = -shared
 LIBS = -lpthread 
 C_FLAGS = $(CPLUS_FLAGS)
--- a/build/linux.gcc.inc
+++ b/build/linux.gcc.inc
@@ -12,8 +12,8 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-CPLUS ?= g++
-CONLY ?= gcc
+CPLUS ?= $(CXX)
+CONLY ?= $(CC)
 COMPILE_ONLY = -c -MMD
 PREPROC_ONLY = -E -x c++
 INCLUDE_KEY = -I