GCC 4.4 fails on #elif without a conditional clause. The attached patch fixes this in Ruby 1.9.1
Created attachment 189410 [details, diff]
Patch to allow ruby-1.9.1 to build with gcc-4.4
Patch looks perfectly cool.
The patch works on dev-lang/ruby-1.9.1-r99 as well.
Added ruby-1.9.1_p129 to the tree, upstream already made that GCC-4.4 compliant.