fix(make): only generate makefile for multiple toolsets if requested (#…

…133)

It's already like this in the msvs and ninja generators.

Refs: nodejs/node#40934

pylib/gyp/generator/make.py

@@ -50,7 +50,7 @@
 }
 
 # Make supports multiple toolsets
-generator_supports_multiple_toolsets = True
+generator_supports_multiple_toolsets = gyp.common.CrossCompileRequested()
 
 # Request sorted dependencies in the order from dependents to dependencies.
 generator_wants_sorted_dependencies = False