Merge pull request #66 from Kobzol/use-mirror-for-deps

Use rust-lang mirror for downloading GCC dependencies

libgccjit: Add support for the x87 CPU feature

libgccjit: Add the function attributes for setting the ABI

libgccjit: Fix for -fanalyzer used in libgccjit

libgccjit: Fix infinite recursion in gt_ggc_mx_lang_tree_node

This issue happened when compiling rustc with rustc_codegen_gcc, more
specifically when compiling its rustc_parse crate.

gcc/jit/
	PR target/105827
	* dummy-frontend.cc: Fix lang_tree_node.
	* jit-common.h: New function (jit_tree_chain_next) used by
	lang_tree_node.