message: guix: Bump glibc and linux-headers
  Bump glibc and linux-headers to match those of our Gitian counterparts.
  We also require a glibc >= 2.28 for the test-symbol-check scripts to
  work properly.
  The default BASE-GCC-FOR-LIBC also has to be bumped since glibc 2.31
  requires a gcc >= 6.2
diff: @@ -125,9 +125,9 @@ chain for " target " development."))
  (define* (make-bitcoin-cross-toolchain target
  #:key
  - (base-gcc-for-libc gcc-5)
  - (base-kernel-headers linux-libre-headers-4.19)
  - (base-libc glibc-2.27)
  + (base-gcc-for-libc gcc-7)
  + (base-kernel-headers linux-libre-headers-5.4)
  + (base-libc glibc) ; glibc 2.31
  (base-gcc (make-gcc-rpath-link gcc-9)))
  "Convenience wrapper around MAKE-CROSS-TOOLCHAIN with default values
  desirable for building Bitcoin Core release binaries."
  @@ -232,12 +232,6 @@ chain for " target " development."))
  (list zip
  (make-mingw-pthreads-cross-toolchain "x86_64-w64-mingw32")
  (make-nsis-with-sde-support nsis-x86_64)))
  - ((string-contains target "riscv64-linux-")
  - (list (make-bitcoin-cross-toolchain target
  - #:base-gcc-for-libc gcc-7)))
  - ((string-contains target "powerpc64le-linux-")
  - (list (make-bitcoin-cross-toolchain target
  - #:base-gcc-for-libc gcc-7)))
  ((string-contains target "-linux-")
  (list (make-bitcoin-cross-toolchain target)))
  ((string-contains target "darwin")
  