Log Message:
webkit-gtk: Adjust WEBKIT_JIT_MACHINE_PLATFORMS per-upstream

Sync WEBKIT_JIT_MACHINE_PLATFORMS (platforms where `webkit-jit'
option is suggested) is enabled by default with
Source/cmake/WebKitFeatures.cmake.

While here also disable ENABLE_C_LOOP when ENABLE_JIT is enabled
(the two options are incompatible).

Should workaround PR pkg/54109.

(No PKGREVISION bump since it should only fix platforms where since
update of webkit-gtk 2.24.0 were broken.)