Add script to regenerate projects using premake (#755)

util/generate_projects.py

@@ -0,0 +1,28 @@
+#!/usr/bin/env python
+
+import sys
+from os import getenv, path
+from subprocess import PIPE, run
+
+PREMAKE_DIR = path.join(path.dirname(__file__), "../projects/premake")
+
+
+def has(prog):
+    return run(["command", "-v", prog], stdout=PIPE, stderr=PIPE).returncode == 0
+
+
+def run_premake(action, os):
+    run([premake, action, os], cwd=PREMAKE_DIR)
+
+
+premake = getenv("PREMAKE", "premake5")
+if not has(premake):
+    print("error: {} is not found", premake, file=sys.stderr)
+    exit(1)
+
+run_premake("gmake2", "bsd")
+run_premake("gmake2", "linux")
+run_premake("gmake2", "macosx")
+run_premake("vs2017", "windows")
+run_premake("vs2019", "windows")
+run_premake("xcode4", "macosx")