Revert "[ci] Disable llvm-gcc"

This reverts commit e1b8e933f099efae3c3e1f5706be19120b44de20.

Let's see if cbfd8597e050f0123e279b692abf7270898a05fb fixed this.
diff --git a/.circleci/config.yml b/.circleci/config.yml
index 90c0940..628170e 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -301,8 +301,8 @@
   build:
     jobs:
       # macOS
-      #- macos-llvm-gcc-4.2
-      #- macos-notest-apple-gcc-i686-4.2
+      - macos-llvm-gcc-4.2
+      - macos-notest-apple-gcc-i686-4.2
       - macos-notest-ios
 
       # both autotools and cmake