Add another autoconf generated file

Fixes gem installation with builtin libffi.

Fixes #1049

ffi.gemspec

@@ -23,7 +23,7 @@ Gem::Specification.new do |s|
   # Add libffi git files
   lfs = `git --git-dir ext/ffi_c/libffi/.git ls-files -z`.split("\x0")
   # Add autoconf generated files of libffi
-  lfs += %w[ configure config.guess config.sub install-sh ltmain.sh missing fficonfig.h.in ]
+  lfs += %w[ compile configure config.guess config.sub install-sh ltmain.sh missing fficonfig.h.in ]
   # Add automake generated files of libffi
   lfs += `git --git-dir ext/ffi_c/libffi/.git ls-files -z *.am */*.am`.gsub(".am\0", ".in\0").split("\x0")
   s.files += lfs.map do |f|