sip: Add SDP crypto context class

Objects of this type keep track of SDP of the local and remote peers,
allow generating offers and answers and codify default policy used for
cryptographic parameters.

tests/meson.build

@@ -138,6 +138,21 @@ t = executable('srtp', test_sources,
                )
 test('srtp', t, env: test_env)
 
+test_sources = [ 'test-sdp-crypto.c' ]
+test_sources += sip_sources
+t = executable('sdp-crypto', test_sources,
+               c_args : test_cflags,
+               link_args: test_link_args,
+               pie: true,
+               link_with : [calls_vala, libcalls],
+               dependencies: [calls_deps, sip_deps],
+               include_directories : [
+                   calls_includes,
+                   sip_include,
+                 ]
+               )
+test('sdp-crypto', t, env: test_env)
+
 test_sources = [ 'test-util.c' ]
 t = executable('util', test_sources,
                c_args : test_cflags,