Properly set PIC flag for libspglib and libtubegen

Signed-off-by: Geoff Hutchison <geoff.hutchison@gmail.com>

Change-Id: Ibe8f103fe3a6bfe0ad7c72c6cdfe37d0c2535899
Merge topic 'FIX_shlib-pic-flag' into master

3adb5714 Properly set PIC flag for libspglib and libtubegen