3.1.9 build fails at zftp.c when using Sun's WorkShop Compilers 5.0

[Roland Jesse <jesse@mail.CS.Uni-Magdeburg.De>]

Building zsh 3.1.9 on a Sun fails when using Sun's compiler version
"WorkShop Compilers 5.0 98/12/15 C 5.0". The build is done using
"./configure --enable-dynamic --enable-zsh-mem && make".

Is there something wrong with my setup or did others experience this
as well?

The error message is:

cc -c -I. -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -DHAVE_CONFIG_H -DMODULE -xO4 -Kpic -o zftp..o zftp.c
"./zftp.pro", line 4: identifier redeclared: inet_aton
        current : static function(pointer to const char, pointer to struct in_addr {union {..} S_un}) returning int
        previous: function(pointer to const char, pointer to struct in_addr {union {..} S_un}) returning int : "/usr/include/arpa/inet.h", line 52
"./zftp.pro", line 6: identifier redeclared: inet_pton
        current : static function(int, pointer to const char, pointer to void) returning int
        previous: function(int, pointer to const char, pointer to void) returning int : "/usr/include/arpa/inet.h", line 54
"./zftp.pro", line 11: identifier redeclared: gethostbyname2
        current : static function(pointer to const char, int) returning pointer to struct hostent {pointer to char h_name, pointer to pointer ...
        previous: function(pointer to const char, int) returning pointer to struct hostent {pointer to char h_name, pointer to pointer to char... : "/usr/include/netdb.h", line 225
"zftp.c", line 1189: cannot recover from previous errors
cc: acomp failed for zftp.c
make[3]: *** [zftp..o] Error 2
make[3]: Leaving directory `/home/stud/jesse/solaris/t/zsh-3.1.9/Src/Modules'
make[2]: *** [modules] Error 1
make[2]: Leaving directory `/home/stud/jesse/solaris/t/zsh-3.1.9/Src'
make[1]: *** [modules] Error 2
make[1]: Leaving directory `/home/stud/jesse/solaris/t/zsh-3.1.9/Src'
make: *** [all] Error 1