[6.5.0] Ignore read-only errors when updating the mtime of the install_base

[bazel-io]

Currently if the --install_base path passed is not writable by the user invoking Bazel, the Bazel client crashes:

❯ bazel --install_base=/some/read/only/path version
FATAL: failed to set timestamp on '/some/read/only/path': (error: 30): Read-only file system

This happens because the Bazel client (unconditionally) attempts to update the mtime of this path:

bazel/src/main/cpp/blaze.cc

Lines 1010 to 1021 in a3c677d

	// Update the mtime of the install base so that cleanup tools can
	// find install bases that haven't been used for a long time
	std::unique_ptr<blaze_util::IFileMtime> mtime(
	blaze_util::CreateFileMtime());
	if (!mtime->SetToNow(blaze_util::Path(startup_options.install_base))) {
	string err = GetLastErrorString();
	BAZEL_DIE(blaze_exit_code::LOCAL_ENVIRONMENTAL_ERROR)
	<< "failed to set timestamp on '" << startup_options.install_base
	<< "': " << err;
	}
	}
	}

This commit updates the client to ignore such errors. See #20373 for context.

Closes #20442.

Commit 7f782e3

PiperOrigin-RevId: 591266054
Change-Id: If53e7cad48cb62406f7883f72b413e4b5a0bb8e2

[iancha1992]

As per: #20442 (comment)

cc: @brentleyjones