SimGear: Properly print compilers in configure.ac

Print $CC and $CXX using the proper configure.ac mechanism

Author: Hans Ulrich Niedermann <hun@n-dimensional.de>
Signed-off-by: Tim Moore <timoore@redhat.com>

configure.ac

@@ -24,8 +24,10 @@ AC_ARG_WITH(cxx,
   esac
 ])
 
-echo CXX = $CXX
-echo CC = $CC
+AC_MSG_CHECKING([CXX])
+AC_MSG_RESULT([$CXX])
+AC_MSG_CHECKING([CC])
+AC_MSG_RESULT([$CC])
 
 dnl Checks for programs.
 AC_PROG_MAKE_SET