There's no need to set FreeBSD-specific pkgconfig path as FreeBSD handles this by itself by moving the file into right location. Also the condition is always false as CMake does not define `FREEBSD` by default.

Potential fix for https://retrace.fedoraproject.org/faf/reports/556333/

Patch by Seb de Graffenried (@Seb-degraff): nothings/stb#1563
Fixes distorted decompressed audio when UBSan was enabled.

Based on the patches by Jaroslav Lobačevski (@JarLob) submitted
to mainstream at: nothings/stb#1554 and
nothings/stb#1555

GHSL-2023-166/CVE-2023-45676: Multi-byte write heap buffer overflow in start_decoder()
GHSL-2023-167/CVE-2023-45677: Heap buffer out of bounds write in start_decoder()

Based on the patches by Jaroslav Lobačevski (@JarLob) submitted
to mainstream at: nothings/stb#1557 and
nothings/stb#1558

GHSL-2023-169/CVE-2023-45679: Attempt to free an uninitialized memory pointer in vorbis_deinit()
GHSL-2023-170/CVE-2023-45680: Null pointer dereference in vorbis_deinit()

Based on patch by Jaroslav Lobačevski (@JarLob) submitted to
mainstream at nothings/stb#1559

GHSL-2023-171/CVE-2023-45681: Out of bounds heap buffer write

Based on patch by Jaroslav Lobačevski (@JarLob) submitted to
mainstream at nothings/stb#1560

GHSL-2023-172/CVE-2023-45682: Wild address read in vorbis_decode_packet_rest()

c.f.: nothings/stb#1248.

(c.f.: nothings/stb#1248,
       nothings/stb#1554 ,
       nothings/stb#1555 )

Add SDLSOUND_BUILD_DOCS option to control whether build docs