sdl12-compat: CI: Need the Mesa headers for testgl.c

From 229f0ec891885ce2a96f6ccc391ee12e30fe455c Mon Sep 17 00:00:00 2001
From: "Ryan C. Gordon" <[EMAIL REDACTED]>
Date: Tue, 1 Jun 2021 20:42:49 -0400
Subject: [PATCH] CI: Need the Mesa headers for testgl.c

---
 .github/workflows/main.yml | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 684f80c..24c63bf 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -17,7 +17,7 @@ jobs:
       if: runner.os == 'Linux'
       run: |
         sudo apt-get update
-        sudo apt-get install cmake ninja-build
+        sudo apt-get install cmake ninja-build libgl1-mesa-dev
     - name: Get sdl12-compat sources
       uses: actions/checkout@v2
     - name: Get SDL2 headers
@@ -28,7 +28,5 @@ jobs:
         path: SDL2
     - name: Configure CMake
       run: cmake -DSDL2_INCLUDE_DIR="${{ github.workspace }}/SDL2/include" -B build ${{ matrix.platform.flags }}
-    - name: debugging
-      run: find "${{ github.workspace }}"
     - name: Build
       run: cmake --build build/