res_pjsip: Add 'suppress_q850_reason_headers' option to endpoint

A new option 'suppress_q850_reason_headers' has been added to the
endpoint object. Some devices can't accept multiple Reason headers and
get confused when both 'SIP' and 'Q.850' Reason headers are received.
This option allows the 'Q.850' Reason header to be suppressed.
The default value is 'no'.

ASTERISK-27949
Reported-by: Ross Beer

Change-Id: I54cf37a827d77de2079256bb3de7e90fa5e1deb1

contrib/ast-db-manage/config/versions/19b00bc19b7b_add_suppress_q850_reason_headers_to_.py

@@ -0,0 +1,27 @@
+"""add suppress_q850_reason_headers to endpoint
+
+Revision ID: 19b00bc19b7b
+Revises: 0be05c3a8225
+Create Date: 2018-07-06 06:30:32.196669
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '19b00bc19b7b'
+down_revision = '0be05c3a8225'
+
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects.postgresql import ENUM
+
+YESNO_NAME = 'yesno_values'
+YESNO_VALUES = ['yes', 'no']
+
+def upgrade():
+    yesno_values = ENUM(*YESNO_VALUES, name=YESNO_NAME, create_type=False)
+    op.add_column('ps_endpoints', sa.Column('suppress_q850_reason_header', yesno_values))
+
+def downgrade():
+    if op.get_context().bind.dialect.name == 'mssql':
+        op.drop_constraint('ck_ps_endpoints_suppress_q850_reason_header_yesno_values','ps_endpoints')
+    op.drop_column('ps_endpoints', 'suppress_q850_reason_header')