fix --srcdir make error (FSBUILD-211)

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@15673 d0543943-73ff-0310-b7d9-9358b9ac24b2

Makefile.am

@@ -222,8 +222,8 @@ endif
 
 bin_SCRIPTS = scripts/gentls_cert scripts/fsxs
 
-src/include/switch_swigable_cpp.h: src/include/switch_cpp.h
-	$(CC) -E src/include/switch_cpp.h -DSWITCH_DECLARE_CLASS= -DSWITCH_DECLARE\(x\)=x -DSWITCH_DECLARE_CONSTRUCTOR= -DSWITCH_DECLARE_NONSTD\(x\)=x 2>/dev/null | grep -v "^#" > src/include/switch_swigable_cpp.h 
+src/include/switch_swigable_cpp.h: $(switch_srcdir)/src/include/switch_cpp.h
+	$(CC) -E $(switch_srcdir)/src/include/switch_cpp.h -DSWITCH_DECLARE_CLASS= -DSWITCH_DECLARE\(x\)=x -DSWITCH_DECLARE_CONSTRUCTOR= -DSWITCH_DECLARE_NONSTD\(x\)=x 2>/dev/null | grep -v "^#" > src/include/switch_swigable_cpp.h 
 
 libs/libedit/src/.libs/libedit.a:
 	cd libs/libedit && $(MAKE)