configure script needs to test for g++ 4.8 and above.

Added a check to test the version of g++ in the configure script.
Also did a "which" command to save the full path of the CC and CXX
commands.  This will ensure that the same CC and CXX executables
are run no matter how the environment changes.

refs #255

autoconf/configure.ac

@@ -2,7 +2,7 @@ dnl To generate a new top level configure script from this autoconf directory
 dnl 1.  aclocal
 dnl 2.  autoconf -o ../configure
 
-AC_INIT([Trick],[16.0])
+AC_INIT([Trick],[16+])
 AC_LANG(C++)
 
 AC_CONFIG_AUX_DIR([autoconf])
@@ -166,9 +166,25 @@ CFLAGS="$CFLAGS $XTRAINCPATHS"
 CPPFLAGS="$CPPFLAGS $XTRAINCPATHS"
 
 dnl look for programs we need to compile and run
+AC_PROG_AWK
 AC_PROG_CC
 AC_PROG_CXX
 AC_PROG_LEX
+AX_GCC_VERSION
+dnl if the compiler is gcc, test for gcc >= 4.8
+AS_IF([test "x$GCC_VERSION" = "x"],[],
+ [AC_MSG_CHECKING([gcc version >= 4.8])
+  AX_COMPARE_VERSION([$GCC_VERSION],[ge],[4.8], [AC_MSG_RESULT([yes])],
+   [AC_MSG_RESULT([no])
+    AC_MSG_ERROR([Trick requires gcc version >= 4.8])
+   ])
+])
+dnl AC_PATH_PROG(CC, $CC, no_cc)
+dnl AC_PATH_PROG(CXX, $CXX, no_cxx)
+dnl Save the full path of the compiler
+CC=`which $CC`
+CXX=`which $CXX`
+
 AS_IF([test "x$LEX" = "x:"],AC_MSG_ERROR([could not find flex]),[])
 AC_PATH_PROG(BISON, bison, nobison)
 AS_IF([test "$ac_cv_path_BISON" = "nobison"],AC_MSG_ERROR([could not find bison]),[])