Fix test_asm_pgo on Windows by using response files. The test failed by exceeding Windows command line length limitations, giving an error "WindowsError: [Error 87] The parameter is incorrect". Also extend the logging given by EM_BUILD_VERBOSE=3 to print out the compiler invokations.
Merge pull request #1772 from juj/fix_test_asm_pgo_windows

Fix test_asm_pgo on Windows.