bootstrap: fix use of deprecated -Xmanifest flag

[MaxDesiatov]

We should use -Xbuild-tools-swiftc instead, as the deprecation warning recommends.

[MaxDesiatov]

@swift-ci smoke test

[MaxDesiatov]

macOS failure:

--- bootstrap: note: Building SwiftPM (with a freshly built swift-bootstrap)
Error: Missing value for '-c <configuration>'
Help:  -c <configuration>  Build with configuration
Usage: swift-bootstrap [--package-path <package-path>] [--scratch-path <scratch-path>] [--configuration <configuration>] [-Xcc <Xcc> ...] [-Xswiftc <Xswiftc> ...] [-Xlinker <Xlinker> ...] [-Xcxx <Xcxx> ...] [--verbose] [--very-verbose] [--use-integrated-swift-driver]
  See 'swift-bootstrap --help' for more information.

I wonder if this could be caused by a bug in ArgumentParser?

[neonichu]

IIRC, swift-bootstrap has its own set of arguments that's more restrictive than regular swift build, so we may need to add the new argument there. It doesn't need deprecation since it is supposed to be build from source when used, so maybe we can just rename it.

[MaxDesiatov]

@swift-ci smoke test

[MaxDesiatov]

@swift-ci test windows