add option to disable srtp with --disble-srtp

Makefile.am

@@ -106,7 +106,10 @@ CORE_CFLAGS += -I$(switch_srcdir)/libs/spandsp/src -I$(switch_srcdir)/libs/tiff-
 
 CORE_LIBS  = libs/apr-util/libaprutil-1.la libs/apr/libapr-1.la
 CORE_LIBS += libs/sqlite/libsqlite3.la libs/pcre/libpcre.la libs/speex/libspeex/libspeexdsp.la
+if ENABLE_SRTP
+CORE_CFLAGS += -DENABLE_SRTP
 CORE_LIBS += libs/srtp/libsrtp.la
+endif
 
 MOD_LINK      = $(switch_srcdir)/libfreeswitch.la
 CLEANFILES    = src/include/switch_version.h src/include/switch_swigable_cpp.h

configure.in

@@ -347,6 +347,11 @@ AC_ARG_ENABLE(cpp,
 
 AM_CONDITIONAL([ENABLE_CPP],[test "${enable_cpp}" = "yes"])
 
+AC_ARG_ENABLE(srtp,
+[AC_HELP_STRING([--disable-srtp],[build without srtp support])],[enable_srtp="$enableval"],[enable_srtp="yes"])
+
+AM_CONDITIONAL([ENABLE_SRTP],[test "${enable_srtp}" = "yes"])
+
 AC_ARG_ENABLE(zrtp,
 	[AS_HELP_STRING([--enable-zrtp], [Compile with zrtp Support])],,[enable_zrtp="no"])
 if test "x$enable_zrtp" = "xyes" ; then