Merge bitcoin/bitcoin#33178: guix: increase maximum allowed (runtime) GCC to 7

776a163 guix: increase maximum allowed (runtime) GCC to 7 (fanquake)

Pull request description:

  Fixes:
  ```bash
  /distsrc-base/distsrc-d3b8a54a8120-x86_64-linux-gnu/build/bin/bitcoind: symbol __divmodti4 from unsupported version GCC_7.0.0(14)
  /distsrc-base/distsrc-d3b8a54a8120-x86_64-linux-gnu/build/bin/bitcoind: failed IMPORTED_SYMBOLS
  ```

  which is occuring after #32750. I can't see any supported distro that is shipping a new enough glibc (2.31), but a GCC older than 7.0.

  Fixes #33177.

ACKs for top commit:
  hebasto:
    ACK 776a163.

Tree-SHA512: 8e5a77c509eb6164314fdb644ea199916e151eb0c7f48703f3a2bdedf0dea29b7f402ceacb2aaf42ebffba59080cefbb84253b2721047d973a851090447ba3b5

Author: fanquake

contrib/guix/symbol-check.py

@@ -32,7 +32,7 @@
 # See https://gcc.gnu.org/onlinedocs/libstdc++/manual/abi.html for more info.
 
 MAX_VERSIONS = {
-'GCC':       (4,3,0),
+'GCC':       (7,0,0),
 'GLIBC': {
     lief.ELF.ARCH.X86_64: (2,31),
     lief.ELF.ARCH.ARM:    (2,31),