ci: Remove Python 2 job, update C89 job

Python 2 isn't supported on newer Ubuntu releases. Newer Python
releases have header files which aren't compatible with C89.

Author: nwellnhof

.gitlab-ci.yml

@@ -12,7 +12,12 @@
 gcc:
   extends: .test
   variables:
-    CONFIG: "--without-tls"
+    CFLAGS: "-O2"
+
+gcc:c89:
+  extends: .test
+  variables:
+    CONFIG: "--without-python"
     CFLAGS: "-O2 -std=c89 -D_XOPEN_SOURCE=600"
 
 gcc:minimum:
@@ -36,12 +41,6 @@ gcc:legacy:
     BASE_CONFIG: "--with-legacy"
     CFLAGS: "-O2"
 
-gcc:python3:
-  extends: .test
-  variables:
-    CFLAGS: "-O2"
-    PYTHON: "/usr/bin/python3"
-
 gcc:static:
   extends: .test
   variables: