Remove GCC build for now; add Debug builds

Change-Id: I25612d668bd40ad1cbc68388eadfee8dc0ec99c4

.github/workflows/cmake.yml

@@ -15,38 +15,30 @@ jobs:
       fail-fast: false
 
       # Set up a matrix to run the following 3 configurations:
-      # 1. <Windows, Release, latest MSVC compiler toolchain on the default runner image, default generator>
-      # 2. <Linux, Release, latest GCC compiler toolchain on the default runner image, default generator>
-      # 3. <Linux, Release, latest Clang compiler toolchain on the default runner image, default generator>
-      # 4. <MacOS, Release, latest Clang compiler toolchain on the default runner image, default generator>
+      # 1. <Windows, Release, latest MSVC compiler toolchain on the default runner image, Ninja>
+      # 2. <Linux, Release, latest Clang compiler toolchain on the default runner image, Ninja>
+      # 3. <MacOS, Release, latest Clang compiler toolchain on the default runner image, Ninja>
       #
       # To add more build types (Release, Debug, RelWithDebInfo, etc.) customize the build_type list.
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
-        build_type: [Release]
-        c_compiler: [gcc, clang, cl]
+        build_type: [Debug, Release]
+        c_compiler: [clang, cl]
         include:
           - os: windows-latest
             c_compiler: cl
             cpp_compiler: cl
-          - os: ubuntu-latest
-            c_compiler: gcc
-            cpp_compiler: g++
           - os: ubuntu-latest
             c_compiler: clang
             cpp_compiler: clang++
           - os: macos-latest
             c_compiler: clang
             cpp_compiler: clang++
         exclude:
-          - os: windows-latest
-            c_compiler: gcc
           - os: windows-latest
             c_compiler: clang
           - os: ubuntu-latest
             c_compiler: cl
-          - os: macos-latest
-            c_compiler: gcc
           - os: macos-latest
             c_compiler: cl