gdb is ko on rpi2

$this->bbcode_second_pass_code('', 'gdb spidev_test
gdb: symbol lookup error: /usr/lib/libgc.so.1: undefined symbol: GC_setup_mark_lock')
$this->bbcode_second_pass_code('', 'ls -l /usr/lib/libgc.*
lrwxrwxrwx 1 root root 14 Aug 27 2015 /usr/lib/libgc.so -> libgc.so.1.0.3
lrwxrwxrwx 1 root root 14 Aug 27 2015 /usr/lib/libgc.so.1 -> libgc.so.1.0.3
-rwxr-xr-x 1 root root 129720 Aug 27 2015 /usr/lib/libgc.so.1.0.3')
$this->bbcode_second_pass_code('', 'ls /var/cache/pacman/pkg/gdb*
/var/cache/pacman/pkg/gdb-7.9.1-1-armv7h.pkg.tar.xz')
Manually building and running gdb from source files @ http://ftp.gnu.org/gnu/gdb/
works fine.
lah