[deps/mpfr]: sync build flags with Yggdrasil/MPFR

[inkydragon]

• sync
  https://github.com/JuliaPackaging/Yggdrasil/blob/b2e0c2c5851b71230fb7170f74d773393ce37f80/M/MPFR/build_tarballs.jl#L17
• build versioned lib
  

  julia/stdlib/MPFR_jll/src/MPFR_jll.jl

  Line 21 in 95ea594

  const libmpfr = "libmpfr-6.dll"

• do some clean

[inkydragon]

config.sub is added in commit: efe367d

Only mpfr still need config.sub.

julia/deps/mpfr.mk

Line 35 in 89bdcce

cp $(SRCDIR)/patches/config.sub $(SRCCACHE)/mpfr-$(MPFR_VER)/config.sub

Three years passed, and I would like to ask @Keno if we still need this patch file.

[vtjnash]

Three years passed, and I would like to ask @Keno if we still need this patch file.

Still needed. Looking at mpfr-4.1.0 (latest) release, it is over 2 years old and the config.sub file was old even at that time (from 2018)

[ViralBShah]

@inkydragon This looks like it is good to merge. Let me know if it is. Also pinging @giordano for a quick look.