travis-ci: remove openssl 1.0.2 and clang compiler mode from travis to save credits. (openresty#356)

Author: xiaocang

.travis.yml

@@ -7,7 +7,6 @@ language: c
 
 compiler:
  - gcc
- - clang
 
 addons:
  apt:
@@ -41,7 +40,6 @@ env:
  - TEST_NGINX_RANDOMIZE=1
  - LUACHECK_VER=0.21.1
  matrix:
- - NGINX_VERSION=1.19.9 OPENSSL_VER=1.0.2u OPENSSL_PATCH_VER=1.0.2h
  - NGINX_VERSION=1.19.9 OPENSSL_VER=1.1.0l OPENSSL_PATCH_VER=1.1.0d
  - NGINX_VERSION=1.19.9 OPENSSL_VER=1.1.1k OPENSSL_PATCH_VER=1.1.1f