gg: add gg.m4, use it in the sokol GLSL examples (#8755)

.github/workflows/sokol_shader_examples.yml

@@ -0,0 +1,44 @@
+name: Sokol Shader Examples
+
+on:
+  push:
+    branches:
+      - master
+    paths-ignore:
+      - "**.md"
+  pull_request:
+    branches:
+      - master
+    paths-ignore:
+      - "**.md"
+
+jobs:
+  sokol-shaders-can-be-compiled:
+    runs-on: ubuntu-20.04
+    timeout-minutes: 30
+    env:
+      VFLAGS: -cc tcc -no-retry-compilation
+    steps:
+      - uses: actions/checkout@v2
+      - name: Install dependencies
+        run: |
+          sudo rm -f /etc/apt/sources.list.d/dotnetdev.list /etc/apt/sources.list.d/microsoft-prod.list; sudo apt-get update;
+          sudo apt-get install --quiet -y libglfw3 libglfw3-dev libfreetype6-dev  libxi-dev libxcursor-dev libasound2-dev xfonts-75dpi xfonts-base
+      - name: Build v
+        run: |
+          echo $VFLAGS
+          make -j4
+          ./v -cg -cflags -Werror -o v cmd/v
+      - name: Shader examples can be build
+        run: |
+          wget https://github.com/floooh/sokol-tools-bin/archive/pre-feb2021-api-changes.tar.gz
+          tar -xf pre-feb2021-api-changes.tar.gz
+          for f in examples/sokol/02_cubes_glsl/cube_glsl \
+              examples/sokol/03_march_tracing_glsl/rt_glsl \
+              examples/sokol/04_multi_shader_glsl/rt_glsl_puppy \
+              examples/sokol/04_multi_shader_glsl/rt_glsl_march \
+              ; do \
+                 echo "compiling shader $f.glsl ..."; \
+                 sokol-tools-bin-pre-feb2021-api-changes/bin/linux/sokol-shdc --input $f.glsl --output $f.h --slang glsl330 ; \
+          done
+          for vfile in examples/sokol/0?*/*.v; do echo "compiling $vfile ..."; ./v $vfile ; done