Generate an error if no valid gcc is found when configure runs.

Close #3385.

aclocal/check-tool.m4

@@ -0,0 +1,9 @@
+## Check for a cross tool, similar to AC_CHECK_TOOL, but do not fall back to
+## the un-prefixed version of PROG-TO-CHECK-FOR.
+dnl RTEMS_CHECK_TOOL(VARIABLE, PROG-TO-CHECK-FOR[, VALUE-IF-NOT-FOUND [, PATH]])
+AC_DEFUN([RTEMS_CHECK_TOOL],
+[
+  AS_IF([test "x$target_alias" != "x$host_alias"],
+    [rtems_tool_prefix=$target_alias-])
+  AC_CHECK_PROG($1, ${rtems_tool_prefix}$2, ${rtems_tool_prefix}$2, $3, $4)
+])

configure.ac

@@ -25,12 +25,16 @@ RTEMS_ENABLE_MULTIPROCESSING
 RTEMS_ENABLE_POSIX
 RTEMS_ENABLE_NETWORKING
 RTEMS_ENABLE_CXX
-RTEMS_ENABLE_TESTS  
+RTEMS_ENABLE_TESTS
 RTEMS_ENABLE_RTEMS_DEBUG
 RTEMS_ENABLE_RTEMSBSP
 RTEMS_ENABLE_PARAVIRT
 RTEMS_ENABLE_DRVMGR
 
+## Check if there are valid tools install and in the path.
+RTEMS_CHECK_TOOL(RTEMS_CC,gcc)
+test -z "$RTEMS_CC" && AC_MSG_ERROR([no acceptable cc found in \$PATH])
+
 ## NOTES:
 ## * tools/build are host-native tools to be installed on the host.
 ## * tools/cpu are host-native or host-cross-target-tools