ruby: add `removeReferenceToCC` package option

Reduces the runtime closure by ~200MB if enabled.

pkgs/development/interpreters/ruby/default.nix

@@ -3,7 +3,7 @@
 , zlib, openssl, gdbm, ncurses, readline, groff, libyaml, libffi, autoreconfHook, bison
 , autoconf, libiconv, libobjc, libunwind, Foundation
 , buildEnv, bundler, bundix
-, makeWrapper, buildRubyGem, defaultGemConfig
+, makeWrapper, buildRubyGem, defaultGemConfig, removeReferencesTo
 } @ args:
 
 let
@@ -44,6 +44,11 @@ let
       , groff, docSupport ? true
       , libyaml, yamlSupport ? true
       , libffi, fiddleSupport ? true
+      # ruby -e "puts RbConfig::CONFIG['configure_args']"
+      # puts a reference to the C compiler in the binary.
+      # This might be required by some gems at runtime,
+      # but we allow to strip it out for smaller closure size.
+      , removeReferencesTo, removeReferenceToCC ? false
       , autoreconfHook, bison, autoconf
       , buildEnv, bundler, bundix
       , libiconv, libobjc, libunwind, Foundation
@@ -145,6 +150,13 @@ let
           # Remove unnecessary groff reference from runtime closure, since it's big
           sed -i '/NROFF/d' $out/lib/ruby/*/*/rbconfig.rb
 
+          ${lib.optionalString removeReferenceToCC ''
+              # Get rid of the CC runtime dependency
+              ${removeReferencesTo}/bin/remove-references-to \
+                -t ${stdenv.cc} \
+                $out/lib/libruby.so.*
+          ''}
+
           # Bundler tries to create this directory
           mkdir -p $out/nix-support
           cat > $out/nix-support/setup-hook <<EOF