Do not place dependency upon mozilla meta-build targets as we're not parallel-safe across build phases.

Bug #183263 r=bryner,dcran a=asa

xpcom/typelib/xpidl/Makefile.in

@@ -79,4 +79,5 @@ HOST_CFLAGS	+= -DMDCPUCFG=$(HOST_NSPR_MDCPUCFG)
 endif
 endif
 
-export:: libs
+export::
+	@$(MAKE) libs

xpcom/typelib/xpt/src/Makefile.in

@@ -49,7 +49,8 @@ HOST_CFLAGS	+= -DEXPORT_XPT_API
 
 # Build libxpt early so that it'll be available to xpidl, which also
 # must be built early.
-export:: libs
+export::
+	@$(MAKE) libs
 
 ifdef CROSS_COMPILE
 ifdef HOST_NSPR_MDCPUCFG

xpcom/typelib/xpt/tools/Makefile.in

@@ -67,7 +67,8 @@ endif
 
 
 # Build xpt_link and xpt_dump early.  (libs creates .deps used by libs.)
-export:: libs
+export::
+	@$(MAKE) libs