RISC-V: jal cannot refer to a default visibility symbol for shared object.

This is the original binutils bugzilla report,
https://sourceware.org/bugzilla/show_bug.cgi?id=28509

And this is the first version of the proposed binutils patch,
https://sourceware.org/pipermail/binutils/2021-November/118398.html

After applying the binutils patch, I get the the unexpected error when
building libgcc,

/scratch/nelsonc/riscv-gnu-toolchain/riscv-gcc/libgcc/config/riscv/div.S:42:
/scratch/nelsonc/build-upstream/rv64gc-linux/build-install/riscv64-unknown-linux-gnu/bin/ld: relocation R_RISCV_JAL against `__udivdi3' which may bind externally can not be used when making a shared object; recompile with -fPIC

Therefore, this patch add an extra hidden alias symbol for __udivdi3, and
then use HIDDEN_JUMPTARGET to target a non-preemptible symbol instead.
The solution is similar to glibc as follows,
https://sourceware.org/git/?p=glibc.git;a=commit;h=68389203832ab39dd0dbaabbc4059e7fff51c29b

libgcc/ChangeLog:

	* config/riscv/div.S: Add the hidden alias symbol for __udivdi3, and
	then use HIDDEN_JUMPTARGET to target it since it is non-preemptible.
	* config/riscv/riscv-asm.h: Added new macros HIDDEN_JUMPTARGET and
	HIDDEN_DEF.