databases/rocksdb: Fix build with PIE

RocksDB's build_detect_platform sets PROFILING_FLAGS=-pg when the compiler
supports it. The two benchmark targets table_reader_bench and log_write_bench
are then linked with -pg, which causes the linker to pull in FreeBSD's gcrt1.o
(the profiling CRT). gcrt1.o contains R_X86_64_64 absolute relocations that are
incompatible with -pie, resulting in a link failure when WITH_PIE=yes is set.

PR: 295260
Approved by: sunpoet (maintainer)
Sponsored by: Netflix