toolchain: fix libgcc ABI for libc

toolchain: fix libgcc ABI for libc

libc depends on knowing libgcc's ABI, so it needs to be evaluated first.
Otherwise libc will depend on an ABI-less libgcc causing the rest of the
toolchain to fail.

Building package index...
ERROR: unable to select packages:
  libgcc (virtual):
    note: please select one of the 'provided by'
          packages explicitly
    provided by: libgcc1
    required by: world[libgcc]

Before:

libc fused dependencies: libgcc
libgcc fused dependencies:
libatomic fused dependencies: libgcc1

After:

libgcc fused dependencies:
libc fused dependencies: libgcc1
libatomic fused dependencies: libgcc1

Signed-off-by: George Sapkin <george@sapk.in>
Link: https://github.com/openwrt/openwrt/pull/21265
Signed-off-by: Robert Marko <robimarko@gmail.com>