Merge pull request #4579 from jboeuf/security_connector_fixes-0_12

src/core/client_config/connector.h

src/core/client_config/subchannel.c

src/core/httpcli/httpcli_security_connector.c

src/core/security/client_auth_filter.c

src/core/security/credentials.c

src/core/security/handshake.c

src/core/security/security_connector.c

src/core/security/security_connector.h

src/core/security/server_secure_chttp2.c

src/core/surface/channel_create.c

src/core/surface/secure_channel_create.c

test/core/security/security_connector_test.c