[OpenMP] Use generic IR for the OpenMP DeviceRTL (#119091)

Summary:
We previously built this for every single architecture to deal with
incompatibility. This patch updates it to use the 'generic' IR that
`libc` and other projects use. Who knows if this will have any
side-effects, probably worth testing more but it passes the tests I
expect to pass on my side.
GitOrigin-RevId: 34f8573a514915222630cf21e8a0c901a25f4ca0
1 file changed