build: add linux premake5 binary

Add linux premake binary for 32 and 64 bit Linuxes. premake5-linux
script does a naive 32/64 bit test, and runs the appropriate binary.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@iki.fi>

build/premake5-linux

@@ -0,0 +1,8 @@
+#!/bin/sh
+
+if [ $(uname -m) = "x86_64" ]; then
+	./premake5-linux-64 $*
+else
+	./premake5-linux-32 $*
+fi
+