check if c++17 headers are there.

Author: Decapitated

.github/workflows/builds.yml

@@ -76,7 +76,7 @@ jobs:
         run: |
           sudo apt-get install tree
           pwd
-          tree
+          tree /usr/include/c++
           scons target=${{ matrix.target-type }} platform=${{ matrix.target.platform }} arch=${{ matrix.target.arch }} precision=${{ matrix.float-precision }}
 
       # Sign the binary (macOS only)