chan_pjsip: add a flag to ignore 183 responses if no SDP present

chan_sip will always ignore 183 responses that do not contain SDP
however, chan_pjsip will currently always translate it into a
183 with SDP.  This new flag allows chan_pjsip to have the same
behavior as chan_sip.

ASTERISK-28322 #close

Change-Id: If81cfaa17c11b6ac703e3d71696f259d86c6be4a

contrib/ast-db-manage/config/versions/80473bad3c16_ignore_183_without_sdp.py

@@ -0,0 +1,38 @@
+"""ignore 183 without sdp
+
+Revision ID: 80473bad3c16
+Revises: f3c0b8695b66
+Create Date: 2019-03-04 08:30:51.592907
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '80473bad3c16'
+down_revision = 'f3c0b8695b66'
+
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects.postgresql import ENUM
+
+AST_BOOL_NAME = 'ast_bool_values'
+# We'll just ignore the n/y and f/t abbreviations as Asterisk does not write
+# those aliases.
+AST_BOOL_VALUES = [ '0', '1',
+                    'off', 'on',
+                    'false', 'true',
+                    'no', 'yes' ]
+
+def upgrade():
+    ############################# Enums ##############################
+
+    # ast_bool_values has already been created, so use postgres enum object
+    # type to get around "already created" issue - works okay with mysql
+    ast_bool_values = ENUM(*AST_BOOL_VALUES, name=AST_BOOL_NAME, create_type=False)
+
+    op.add_column('ps_endpoints', sa.Column('ignore_183_without_sdp', ast_bool_values))
+
+def downgrade():
+    if op.get_context().bind.dialect.name == 'mssql':
+        op.drop_constraint('ck_ps_endpoints_ignore_183_without_sdp_ast_bool_values', 'ps_endpoints')
+    op.drop_column('ps_endpoints', 'ignore_183_without_sdp')
+    pass