Update GCC to the 8.1 release

This has no additional patches, but it does result in a whole host of
test suite failures.

Update binutils to the 2.30 release

This has no additional patches on top of the upstream release.

Split the binutils and GDB builds

Binutils and GDB are kept in the same repository but follow seperate
relaese streams.  We've been release GDB versions based on binutils
tags, but this is the wrong thing to do and has caused multiple
headaches related to our out-of-tree GDB port.

This patch splits the binutils and GDB submodules, but doesn't actually
change the versions.

Remove bashism from download_prerequisites check

This change is to fix an error which prevents the Makefile
from downloading gmp, mpfr, mpc, and isl on systems with a
bourne shell.

Bump gdb

Bump gdb

Make linux-native builds work again.

expat is required by cross for OpenOCD support, but not provided for native
builds, so replace BINUTILS_GDB_TARGET_FLAGS with BINUTILS_GDB_NATIVE_FLAGS.

Set CC_FOR_TARGET when configuring cross binutils.

This is required to make the ld testsuite work correctly, as some tests
require a compiler.

Force --with-expat to be enabled for gdb, since OpenOCD requires it.

Add BINUTILS_GDB_TARGET_FLAGS, init to --with-expat=yes, and pass to all 3 gdb
configure commands.  Update README.md to list expat package names.

248124ac2e RISC-V: Add missing privileged spec registers.
bee792f83a RISC-V: Add compressed instruction hints, and a few misc cleanups.
7d895b6f4c Add missing RISC-V fsrmi and fsflagsi instructions.
04d33e4a83 Objcopy interleave fails if section address not multiple of interleave.
71a8fbb5aa Really fix riscv shared library __global_pointer$ problem.
355497b4a7 Riscv shared libraries should not export __global_pointer$.
bfd4dc4363 Fix for texinfo 4.8.
caf839a4a4 Update and clean up RISC-V gas documentation.
df726395c9 Give Palmer co-credit for last patch.
0362ab46db Fix riscv malloc error on small alignment after norvc.
3adcc16f76 Merge pull request #126 from riscv/native-gdb
be4ba40749 Make native gdb builds work.

Fix relsrcdir problem that breaks regression Makefile.

Rename to mayberelsrcdir, and handle both cases where it can be relative
or absolute when setting gccsrcdir.

Add enable-obsolete-rpc option for glibc

Bump gdb to support XML target description

Make clean remove nano build artifacts.

	* Makefile.in (clean): Add install-newlib-nano dir.

Fix some msys2 (Windows) build failures.

	* Makefile.in (relsrcdir): New.
	(stamps/build-gcc-linux-stage1, stamps/build-gcc-linux-stage2)
	(stamps/build-gcc-newlib-stage1, stamps/build-gcc-newlib/stage2): Pass
	--src to configure set from relsrcdir.

Enable this option to build the obsolete RPC implementation.
Some projects still uses these headers like: LTP, Busybox and so on.

Add newlib nano support.

This might be an actaul newlib bug: it's not providing a range error
when taking log1p of -1e80, but it appears that this triggered a glibc
bug from a while ago that may have not been fixed in newlib.  I'm not
sure why the bug is just manifesting now (the newlib sources haven't
changed for a long time), but the glibc version has some macros that
force the evaluation of particular floating-point expressions (one of
which produces the range error) that don't exist in newlib.

I'm OK whitelisting the error for the next release, despite it
technically being a regression.  log1p isn't a standard function, and I
doubt embedded users are going to notice.  That said, we should still
fix it.

	* Makefile.in (NEWLIB_NANO_TARGET_BOARDS): New.
	(build-libc): Change build-newlib to stamps/build-newlib.  Add
	stamps/build-newlib-nano.
	(check-newlib-nano, check-gcc-newlib-nano, check-binutils-newlib-nano)
	(check-gdb-newlib-nano, report-newlib-nano): New.
	(check-dhrystone-linux, check-dhrystone-newlib): Delete first version
	of these rules.
	(build-gcc-newlib-stage1): Use --with-sysroot.
	(build-newlib-nano, merge-newlib-nano): New.
	(build-gcc-newlib-stage2): Depend on merge-newlib-nano.  Use
	--with-sysroot instead of --with-headers.  Also use
	--with-native-system-header-dir.
	(build-dejagnu): Install it.
	(check-gcc-newlib, check-gcc-linux, check-dhrystone-newlib-%)
	(check-dhrystone-linux-%, check-binutils-newlib, check-binutils-linux)
	(check-gdb-newlib, check-gdb-linux): Drop
	DEJAGNULIBS environment variable set.
	(check-gcc-newlib-nano, check-dhrystone-newlib-nano)
	(check-dhrystone-newlib-nano-%, check-binutils-newlib-nano)
	(check-gdb-newlib-nano, report-gcc-newlib-nano)
	(report-dhrystone-newlib-nano, report-binutils-newlib-nano)
	(report-gdb-newlib-nano): New.
	(Makefile): Add rule to rebuild when Makefile.in changes.
	(test/benchmarks/dhrystone/check): Add -specs= option.  Use it in
	$cc commands.

https://github.com/riscv/riscv-gnu-toolchain/issues/296

b731149757b9 RISC-V: Implement movmemsi
605bc7b5e06a RISC-V: Define MUSL_DYNAMIC_LINKER

d0176cb1653b RISC-V: Fix riscv g++ testsuite EH failures.
d5feabfac32f RISC-V: Add satp as an alias for sptbr