postgresql: disable PIC

postgresql: disable PIC

with PIC enabled, build fails with
ld: access/gist/gistproc.o: in function `rtree_internal_consistent':
gistproc.c:(.text+0x188): relocation truncated to fit: R_AARCH64_LD64_GOTPAGE_LO15 against symbol `DirectFunctionCall2Coll' defined in .text section in utils/fmgr/fmgr.o
ld: gistproc.c:(.text+0x188): warning: too many GOT entries for -fpic, please recompile with -fPIC
ld: final link failed: symbol needs debug section which does not exist
collect2: error: ld returned 1 exit status

Related-to: 8e9ad7bb5117edea4df08cd9a2de62685103a4b3
Signed-off-by: Michal Vasilek <michal.vasilek@nic.cz>