[iOS/GN] Add -install_name to the shared_library ldflags on iOS.
[iOS/GN] Add -install_name to the shared_library ldflags on iOS.

The generated dylib will be available to the application via the
framework bundle so add "-install_name @rpath/XXX.framework/XXX"
when using the "ios_framework_bundle" template.

BUG=599321,599322

Review URL: https://codereview.chromium.org/1882423002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#387273}

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