Fix logic for absolute/relative argv[0] when constructing executable path.

Do not call path_isabsolute() in condition -- it always returns 1 and modifies the stack.
If argv[0] is already absolute, push it in the stack alone.

src/host/premake.c

@@ -419,11 +419,12 @@ int premake_locate_executable(lua_State* L, const char* argv0)
 		lua_pushstring(L, "/");
 		lua_pushstring(L, argv0);
 
-		if (!path_isabsolute(L)) {
+		if (!do_isabsolute(argv0)) {
 			lua_concat(L, 3);
 		}
 		else {
-			lua_pop(L, 1);
+			lua_pop(L, 3);
+			lua_pushstring(L, argv0);
 		}
 
 		path = lua_tostring(L, -1);