Quote flags in GN.

Previously cflags/ldflags/etc. were not automatically quoted by GN. The
original intention was to support having multiple flags in one string which we
don in GYP in some cases (e.g. "-foo -bar"). But this ends up not being
necessary and we never do it.

Furthermore, GN still escapes quote characters in these flags, making it
impossible to manually quote them. The result is the old policy actively
prevents using spaces or quotes in flags. This change automatically quotes
flags like defines and file names already were.

Review URL: https://codereview.chromium.org/1879723002

Cr-Original-Commit-Position: refs/heads/master@{#386490}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: d923cf82900e3c26ab4f989cff62bf2bd6c2810f
1 file changed
tree: dd8cf4cd673f4a07b1b2e9bb97dfe43720f93c6b
  1. tools/