I obtain this warning during configure:
configure: WARNING: signal.h: present but cannot be compiled
configure: WARNING: signal.h:     check for missing prerequisite headers?
configure: WARNING: signal.h: see the Autoconf documentation
configure: WARNING: signal.h:     section "Present But Cannot Be Compiled"
configure: WARNING: signal.h: proceeding with the preprocessor's result
configure: WARNING: signal.h: in the future, the compiler will take precedence
configure: WARNING:     ## ------------------------------ ##
configure: WARNING:     ## Report this to the joe lists.  ##
configure: WARNING:     ## ------------------------------ ##

and if I ignore it I coul'd not compile finishing with this error:
make[1]: Entering directory `/Documents/joe-3.1'
if gcc -DHAVE_CONFIG_H -I. -I. -I. -DJOERC="\"/usr/local/etc/joe/\""  -I/usr/local/include  -g -O2 -MT b.o -MD -MP -MF ".deps/b.Tpo" -c -o b.o b.c; \ then mv -f ".deps/b.Tpo" ".deps/b.Po"; else rm -f ".deps/b.Tpo"; exit 1; fi
In file included from /usr/include/sys/signal.h:34,
                 from /usr/include/signal.h:26,
                 from utils.h:19,
                 from b.c:35:
/usr/include/sys/siginfo.h:259: error: parse error before "ctid_t"
/usr/include/sys/siginfo.h:292: error: parse error before '}' token
/usr/include/sys/siginfo.h:294: error: parse error before '}' token
/usr/include/sys/siginfo.h:390: error: parse error before "ctid_t"
/usr/include/sys/siginfo.h:392: error: conflicting types for `__proc'
/usr/include/sys/siginfo.h:261: error: previous declaration of `__proc'
/usr/include/sys/siginfo.h:398: error: conflicting types for `__fault'
/usr/include/sys/siginfo.h:267: error: previous declaration of `__fault'
/usr/include/sys/siginfo.h:404: error: conflicting types for `__file'
/usr/include/sys/siginfo.h:273: error: previous declaration of `__file'
/usr/include/sys/siginfo.h:420: error: conflicting types for `__prof'
/usr/include/sys/siginfo.h:287: error: previous declaration of `__prof'
/usr/include/sys/siginfo.h:424: error: conflicting types for `__rctl'
/usr/include/sys/siginfo.h:291: error: previous declaration of `__rctl'
/usr/include/sys/siginfo.h:426: error: parse error before '}' token
/usr/include/sys/siginfo.h:428: error: parse error before '}' token
/usr/include/sys/siginfo.h:432: error: parse error before "k_siginfo_t"
/usr/include/sys/siginfo.h:437: error: parse error before '}' token
In file included from /usr/include/signal.h:26,
                 from utils.h:19,
                 from b.c:35:
/usr/include/sys/signal.h:85: error: parse error before "siginfo_t"
In file included from utils.h:19,
                 from b.c:35:
/usr/include/signal.h:111: error: parse error before "siginfo_t"
/usr/include/signal.h:113: error: parse error before "siginfo_t"
b.c:2572: error: conflicting types for `ttsig'
tty.h:148: error: previous declaration of `ttsig'
make[1]: *** [b.o] Error 1
make[1]: Leaving directory `/Documents/joe-3.1'
make: *** [all] Error 2

any help is appreciated.. thanks.