Folding build_tools back into the main repo for simplicity.

tools/build/scripts/force_compile_as_c.lua

@@ -0,0 +1,28 @@
+if premake.override then
+  local forced_c_files = {}
+
+  -- Forces all of the given .c and .cc files to be compiled as if they were C.
+  function force_compile_as_c(files)
+    for _, val in ipairs(files) do
+      for _, fname in ipairs(os.matchfiles(val)) do
+        table.insert(forced_c_files, path.getabsolute(fname))
+      end
+    end
+  end
+
+  -- for gmake
+  premake.override(path, "iscfile", function(base, fname)
+    if table.contains(forced_c_files, fname) then
+      return true
+    else
+      return base(fname)
+    end
+  end)
+  -- for msvc
+  premake.override(premake.vstudio.vc2010, "additionalCompileOptions", function(base, cfg, condition)
+    if cfg.abspath and table.contains(forced_c_files, cfg.abspath) then
+      _p(3,'<CompileAs %s>CompileAsC</CompileAs>', condition)
+    end
+    return base(cfg, condition)
+  end)
+end