Bug 500927 - MKDIR definition in agent/Makefile.inc may conflict with VxWorks definition

Updated Makefile.inc to only define MKDIR and RMDIR macros if not
already defined.

Signed-off-by: Jean-Michel Pedrono <jean-michel.pedrono@windriver.com>
diff --git a/agent/Makefile.inc b/agent/Makefile.inc
index c532e5a..3e338ce 100644
--- a/agent/Makefile.inc
+++ b/agent/Makefile.inc
@@ -23,8 +23,12 @@
 SRCDIRS = . system/$(OPSYS)/tcf machine/$(MACHINE)/tcf tcf tcf/framework tcf/services tcf/main
 BINDIR  = obj/$(OPSYS)/$(MACHINE)/$(CONF)
 
+ifndef MKDIR
 MKDIR   = mkdir -p $(1)
+endif
+ifndef RMDIR
 RMDIR   = rm -rf $(1)
+endif
 
 ifeq ($(CONF),Debug)
   OPTS += -g