gollvm: update libgo libffi cmake rules

Revise cmake rules in libgo to allow for additional source files that
have been added recently to libffi.

Updates golang/go#45424.

Change-Id: Ib4f17d1f7f6d418021b3ebac95845a91e794c5a1
Reviewed-on: https://go-review.googlesource.com/c/gollvm/+/308450
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Trust: Than McIntosh <thanm@google.com>
diff --git a/cmake/modules/LibffiUtils.cmake b/cmake/modules/LibffiUtils.cmake
index b3fa697..035b647 100644
--- a/cmake/modules/LibffiUtils.cmake
+++ b/cmake/modules/LibffiUtils.cmake
@@ -43,6 +43,7 @@
   # Pick up correct sources based on arch.
   set(c_srcs
     "${libffi_srcroot}/src/closures.c"
+    "${libffi_srcroot}/src/tramp.c"
     "${libffi_srcroot}/src/prep_cif.c"
     "${libffi_srcroot}/src/types.c"
     "${libffi_srcroot}/src/raw_api.c"