add premake5.lua for building with premake5, only for Windows with Win32 API though

premake5.lua

@@ -0,0 +1,32 @@
+workspace "glfw"
+configurations { "Release", "Debug"}
+architecture "x86_64"
+
+project "glfw"
+kind "StaticLib"
+language "C"
+
+targetdir("build/%{cfg.system}/%{cfg.architecture}/%{cfg.shortname}/bin")
+objdir("build/%{cfg.system}/%{cfg.architecture}/%{cfg.shortname}/bin-int")
+
+includedirs {
+    "include/"
+}
+
+files {
+    "src/window.**",
+    "src/context.**",
+    "src/input.**",
+    "src/internal.**",
+    "src/glfw_config.h.in",
+    "src/init.**",
+    "src/monitor.**"
+}
+
+filter "system:Windows"
+    files {
+        "src/win32_**.c",
+        "src/win32_**.h",
+        "src/wgl_context.**"
+    }
+    defines {"_GLFW_WIN32"}