Add binuitls testsuite pr-24406-1 to the white list for newlib.

This testcase is used to check whether the linker is work normally when both
the --wrap=SYMBOL and -flto are set.  It seems that the current fix only can
work when the wrapped symbol `SYMBOL` is defined in the other files and will be
linked.  See the pr-24406-1 test, the `read` symbol is defined in the glibc’s
libc.so.6, and we will also link the libc.so.6 by the linux toolchain, so it
works.  But the `read` symbol isn’t defined in the newlib, or other linked
objects or archives.  Therefore, the pr-24406-1 testsuite is always failed
for riscv elf toolchain, but seems to work for riscv linux toolchain.

On the other hand, if the wrapped symbol is `read_p`, it isn't defined in the
other linked files, so we also get the error link for the linux toolchain.
The fix in upstream seems not complete.  I suppose that we shoud just skip the
pr-24406-1 testcase until upstream fix or remove it.

Bump gcc

Backport following patches:
- RISC-V: Fix bad insn splits with paradoxical subregs.
- RISC-V: Fix more splitters accidentally calling gen_reg_rtx.
- Fix for PR rtl-optimization/89795

Fix default LINUX_HEADERS_SRCDIR path

The --with-headers argument must point to the `include' subdirectory.

Add option to specify source tree of each component

Fix portability issues

Some implementations of rm(1) are stricter about the ordering of option
and non-option arguments as specified in POSIX.

These wrappers are still necessary on non-GNU platforms; glibc
makefile rules invoke `sed' directly with GNU extensions.

Check write permission to install path before build anything

Clean up rules for patch source, it's no longer used after using submodule

Document problems with using same prefix for more than one build.

Increase the timeout for git command.

Bump gcc to 9.2

Bump binutils

 - Backport following patches:
   - RISC-V: Fix lui relaxation issue with code at address 0.
     - Fix https://github.com/riscv/riscv-binutils-gdb/issues/173

Bump gcc

Bump binutils

Backport following patches:
- RISC-V: Handle g extension in multilib-generator
- RISC-V: Handle extensions combination correctly in multilib-generator.
- RISC-V: Promote type correctly for libcalls
- RISC-V: Fix testcase on rv64
- RISC-V: Raise error on unexpected ISA string at end.

Backport following patches:
  - RISC-V: Fix lui relax failure with relro.
  - RISC-V: Fix minor issues with FP csr instructions

Bump riscv-gcc

backport following patches:

 - RISC-V: Add -malign-data= option.

Apply new whitelist scheme for binutils

Bump binutils

binutils 2.32 with following patches:
 - Kito's 5-part patch set to improve .insn support.
 - RISC-V: Make objdump disassembly work right for binary files.
 - RISC-V: Enable lui relaxation for CODE and MERGE sections.
 - RISC-V: Fix lui argument parsing.
 - RISC-V: Enable 32-bit linux gdb core file support.
 - RISC-V: Don't check ABI flags if no code section.
 - RISC-V: Relax tail/j to c.j for RV64.
 - RISC-V: Fix linker crash in section symbol check.
 - RISC-V: Compress 3-operand beq/bne against x0.

Disable transactional memory support to reduce code size.

Bump riscv-gcc

backport following patches:

 - RISC-V: Fix epilogue unwind info with fp and single sp adjust
 - RISC-V: Generalize -march support, add ELF attribute support.
 - RISC-V: Add libstdc++ check-abi support.
 - RISC-V: Fix %lo overflow with BLKmode references.
 - RISC-V: Add sifive-7 pipeline description.
 - RISC-V: Fix __riscv_compressed regression.
 - RISC-V: Promode modes of constant loads for store insns.
 - RISC-V: Short-forward-branch opt for SiFive 7 series cores.
 - RISC-V: Move STARTFILE_PREFIX_SPEC into target OS files.
 - RISC-V: Fix splitter for 32-bit AND on 64-bit target.
   - https://github.com/riscv/riscv-gcc/issues/161
 - Fix typo in riscv_get_interrupt_type and riscv_merge_decl_attributes.
 - Correctly ignore empty C++ structs when flattening for ABI
 - Add --disable-tm-clone-registry libgcc configure option.