Just FYI the only warning during the build on Haiku is the following...
cc -Iinclude -O2 -g -Wall -Wextra -Wdeclaration-after-statement -fwrapv
-Wno-unused-label -Wno-sign-compare
-Wno-unused-parameter -Wno-clobbered -Wno-missing-field-initializers
-Wno-cast-function-type -Wtype-limits
-Wshift-negative-value -Wshift-overflow=2 -Wduplicated-cond
-Wnull-dereference -DUSE_POLL -DUSE_TPROXY
-DCONFIG_HAPROXY_VERSION=\"2.3-dev6-6b736b-1\"
-DCONFIG_HAPROXY_DATE=\"2020/10/11\" -c -o src/xxhash.o src/xxhash.c
src/xxhash.c:118: warning: "_PACKED" redefined
# define _PACKED
In file included from /boot/system/develop/headers/posix/sys/types.h:11,
from /boot/system/develop/headers/posix/alloca.h:9,
from /boot/system/develop/headers/posix/stdlib.h:9,
from /boot/system/develop/headers/bsd/stdlib.h:9, from
src/xxhash.c:86:
/boot/system/develop/headers/os/BeBuild.h:80: note: this is the location
of the previous definition
#define _PACKED __attribute__((packed))
