Make environment definitions

Make environment definitions.txt

# Using standard definitions from the make environment, typically:
#
#   CC              cc      C compiler
#   CXX             g++     C++ compiler
#   CFLAGS          [ ]     flags for C and C++ compiler
#   CPPFLAGS        [ ]     flags for C and C++ compiler
#   TARGET_ARCH     [ ]     target architecture
#   FFLAGS          [ ]     flags for Fortran compiler
#   RM              rm -f   delete a file
#   AR              ar      create a static *.a library archive
#   ARFLAGS         rv      flags for ar
#   MAKE            make    make itself (sometimes called gmake)