Backport patch for CVE-2021-43618

This backports the patch from 18135:561a9c25298e, addressing CVE-2021-43618 and ghc#22789 (closed).

0003-avoid-bit-size-overflows.patch

+# HG changeset patch
+# User Marco Bodrato <bodrato@mail.dm.unipi.it>
+# Date 1634836009 -7200
+# Node ID 561a9c25298e17bb01896801ff353546c6923dbd
+# Parent  e1fd9db13b475209a864577237ea4b9105b3e96e
+mpz/inp_raw.c: Avoid bit size overflows
+
+diff -r e1fd9db13b47 -r 561a9c25298e mpz/inp_raw.c
+--- a/mpz/inp_raw.c	Tue Dec 22 23:49:51 2020 +0100
++++ b/mpz/inp_raw.c	Thu Oct 21 19:06:49 2021 +0200
+@@ -88,8 +88,11 @@
+ 
+   abs_csize = ABS (csize);
+ 
++  if (UNLIKELY (abs_csize > ~(mp_bitcnt_t) 0 / 8))
++    return 0; /* Bit size overflows */
++
+   /* round up to a multiple of limbs */
+-  abs_xsize = BITS_TO_LIMBS (abs_csize*8);
++  abs_xsize = BITS_TO_LIMBS ((mp_bitcnt_t) abs_csize * 8);
+ 
+   if (abs_xsize != 0)
+     {
+
+