workflows: disable cache, build all branches

.github/workflows/c-cpp.yml

@@ -1,10 +1,16 @@
 name: C/C++ CI
 
 on:
+
   push:
-    branches: [ master ]
+    paths:
+    - src/**
+    - .github/workflows/**
+
   pull_request:
-    branches: [ master ]
+    paths:
+    - src/**
+    - .github/workflows/**
 
 jobs:
   build:
@@ -24,7 +30,6 @@ jobs:
     - uses: msys2/setup-msys2@v1
       with:
         update: true
-        cache: true
         msystem: MINGW32
         install: 'make mingw-w64-i686-toolchain mingw-w64-i686-openal mingw-w64-i686-freetype mingw-w64-i686-SDL2 mingw-w64-i686-zlib mingw-w64-i686-libpng mingw-w64-i686-libvncserver'
     - uses: actions/checkout@v2