Rdar 44142091 fix without test

[davidungar]

Today, response files include extra, bogus quotes, for example: ""foo.swift"". This PR removes the superfluous and harmful extra quotes, so that spaces in file names in response files work.
It fixes rdar://44142091, but cannot be tested easily until #19313 lands. At that point, I will submit another PR with the test, which I have already written:

// RUN: %empty-directory(%t)
// RUN: touch "%t/f i l e.swift"
//
// RUN: %swiftc_driver -driver-force-response-files -typecheck  "%t/f i l e.swift"

Or, if preferred, PR 19313 can land first, then I can add the test to this PR.

[davidungar]

@swift-ci please test

[jrose-apple]

…ouch. Good catch.

[davidungar]

Thanks!

[jrose-apple]

This might also be something worth bringing to the 4.2 branch. It's a very local change that will fix a potentially widespread problem.

[jrose-apple]

(although do wait for the test for that)