switch_xml becomes c again (FSCORE-151)

git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@8941 d0543943-73ff-0310-b7d9-9358b9ac24b2

Makefile.am

@@ -83,7 +83,7 @@ src/switch_ivr_menu.c \
 src/switch_ivr.c \
 src/switch_stun.c\
 src/switch_log.c\
-src/switch_xml.cpp\
+src/switch_xml.c\
 src/switch_config.c\
 src/switch_time.c\
 libs/stfu/stfu.c\