hook-functions: copy_exec: Copy libgcc_s.so with any soversion up to 9

hppa and m68k have higher soversions for libgcc_s.so, so copy
libgcc_s.so.[1-9] instead of assuming soversion 1.

(I considered copying libgcc_s.so.*, but I'm unsure whether that will
ever match extra development files that we don't want.)

Closes: #959768
Signed-off-by: Ben Hutchings <benh@debian.org>