Added extern libraries (Made STB one of them)

Former-commit-id: 0ca555e9f035600924c7c23fff06bc3810051fdf

build/scripts/common_extlibs.lua

@@ -0,0 +1,26 @@
+-- Configuration générale
+configurations 
+{
+	"Debug",
+	"Release"
+}
+
+location("../extlibs/build/" .. _ACTION)
+includedirs "../extlibs/include"
+
+if (_OPTIONS["x64"]) then
+	targetdir "../extlibs/lib/x64"
+else
+	targetdir "../extlibs/lib/x86"
+end
+
+configuration "Debug"
+	flags "Symbols"
+	targetsuffix "-d"
+
+configuration "Release"
+	flags { "EnableSSE", "EnableSSE2", "Optimize", "OptimizeSpeed", "NoFramePointer", "NoRTTI" }
+
+-- Activation du SSE côté GCC
+configuration { "Release*", "codeblocks or codelite or gmake or xcode3*" }
+	buildoptions "-mfpmath=sse"