make can't find sys/signal.h

I’m trying to install m4 in MINGW

After ./configure ended normally I tried make but error was occurred.

make[1]: Entering directory `/c/src/autotools/build_m4/src'
gcc -c -DHAVE_CONFIG_H -I.. -I../../m4-1.4/src -I../../m4-1.4/src/../lib  -g -O
../../m4-1.4/src/m4.c
../../m4-1.4/src/m4.c:22:24: fatal error: sys/signal.h: No such file or director
y
 #include <sys/signal.h>
                        ^
compilation terminated.
make[1]: *** [m4.o] Error 1
make[1]: Leaving directory `/c/src/autotools/build_m4/src'
make: *** [all] Error 1

signal.h is in \c\mingw\include that is set in PATH environment.

How can I tell make where signal.h is?

Solution

Converting a comment into an answer:

On most Unix systems, the file /usr/include/signal.h contains #include <sys/signal.h>. It seems that m4 is assuming that there will be a <sys/signal.h> — presumably without having autoconf check that it exists. This could be a bug in (the configuration process for) m4, or it could be a problem with your setup.

Have you been able to compile other GNU programs before? Is there a directory /c/mingw/include/sys (or \c\mingw\include\sys)? If not, you may be able to get going by creating a sys subdirectory in \c\mingw\include (if it is missing) and copying signal.h into it. But it is a hack workaround for a probable bug.

If this works — as it seems to — check whether your MinGW installation was correct and up to date. If so, report the problem to the maintainers of m4 (email bug-m4 at gnu.org), but check the web site for instructions on how to do that.

Consider removing the copied signal.h as it wasn't there originally. OTOH, you may need it again in the future — but personally, I'd feel happier if the installation were in its pristine state normally and the hack was only made when absolutely necessary.