rustdoc: Document explicit self in methods. Closes #5254
syntax: Fix fun_to_str test
rt: Add RUST_DEBUG_MEM to rust_env to avoid races
auto merge of #5342 : brson/rust/debug-mem, r=brson

Fixes #5341
rustdoc: Show all impls of traits. #5406
auto merge of #5415 : brson/rust/rustdoc, r=thestinger

r? @thestinger
rustdoc: Fix method printing tests
auto merge of #5374 : z0w0/rust/rustdoc-explicit-self, r=z0w0
Update llvm
rust morestack assembly for arm

Conflicts:
	src/rt/arch/arm/morestack.S
mk: target triple rename arm-unknown-android->arm-linux-androideabi
Upgrade llvm change
FIX meta_section_name for macos
Enable arm error handling abi
Enable arm error handling abi 2
Use NDK for building android target objects
Update LLVM
Disable segmented stack when target os is android