Server compilation fails with error while trying to compile trapper:

[...]
gcc -DHAVE_CONFIG_H -I. -I../../../include -g -O2 -I/usr/local/include/mysql -fno-strict-aliasing -pipe -I/usr/local/include -MT nodehistory.o -MD -MP -MF .deps/nodehistory.Tpo -c -o nodehistory.o nodehistory.c
In file included from nodehistory.h:24,
from nodehistory.c:23:
../../../include/comms.h:121: error: expected '=', ',', ';', 'asm' or '_attribute_' before 'zbx_tcp_recv_ext'

• • • Error code 1
      [...]

The problem is that "ssize_t" type is not recognized in comms.h in line:

ssize_t zbx_tcp_recv_ext(zbx_sock_t *s, char **data, unsigned char flags, int timeout);

Including <unistd.h> fixed the problem.

Steps to reproduce:
1) checkout trunk
2) enter trunk directory
3) run: ./bootstrap.sh && ./configure --enable-server --with-mysql && make dbschema > /dev/null && make >/dev/null
4) observer compilation error message