buildsystem: Unbreak the build (infloop) on Asterisk 11+

Apparently r408084 ( https://reviewboard.asterisk.org/r/3212/ ) broke the
build. This patch fixes it by ignoring the .lastclean dependencies if the
MENUSELECT_EMBED variable is not defined.

patches:
  tmp.diff uploaded by wdoekes (License 5674)

Review: https://reviewboard.asterisk.org/r/3228/
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Merged revisions 408193 from http://svn.asterisk.org/svn/asterisk/branches/11
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Merged revisions 408194 from http://svn.asterisk.org/svn/asterisk/branches/12


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@408199 65c4cc65-6c06-0410-ace0-fbb531ad65f3

Makefile

@@ -101,8 +101,6 @@ export LDCONFIG_FLAGS
 export PYTHON
 
 -include makeopts
-# we want the MENUSELECT_EMBED var
--include menuselect.makeopts
 
 # start the primary CFLAGS and LDFLAGS with any that were provided
 # to the configure script
@@ -361,7 +359,7 @@ makeopts.embed_rules: menuselect.makeopts
 $(SUBDIRS): makeopts .lastclean main/version.c include/asterisk/build.h include/asterisk/buildopts.h defaults.h makeopts.embed_rules
 
 ifeq ($(findstring $(OSARCH), mingw32 cygwin ),)
-  ifneq ($(MENUSELECT_EMBED),)
+  ifeq ($(shell grep ^MENUSELECT_EMBED=$$ menuselect.makeopts 2>/dev/null),)
     # Non-windows:
     # ensure that all module subdirectories are processed before 'main' during
     # a parallel build, since if there are modules selected to be embedded the