gn: Don't apply rpath link flags on non-Linux in command_buffer_gles2_tests
gn: Don't apply rpath link flags on non-Linux in command_buffer_gles2_tests

Also fixes whitespace problems related to the target in .gyp files.

BUG=589650
CQ_INCLUDE_TRYBOTS=tryserver.chromium.win:win_optional_gpu_tests_rel

Review URL: https://codereview.chromium.org/1698243002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#388424}

axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk,axinging/chromium-crosswalk