Potential bug on riscv32

[Bo YU]

Hi!

I am porting riscv32 to Debian in a downstream way[0]. Now it has a basic
demo can be run on qemu system. Next we plan to build more riscv32
packages but unfortunately it is blocked by m4(IIRC), when I am trying
to build dh-exec[1] the log is below:

```
/usr/share/aclocal-1.16/vala.m4:23: warning: underquoted definition of
[AM_PROG_VALAC
/usr/share/aclocal-1.16/vala.m4:23:   run info Automake 'Extending aclocal'
/usr/share/aclocal-1.16/vala.m4:23:   or see
https://www.gnu.org/software/automake/manual/automake.html#Extending-aclocal
/usr/bin/m4:/tmp/arAAAAAA/am4tAAAAAA/traces.m4:343: ERROR: end of file in string
/usr/bin/m4:/tmp/arAAAAAA/am4tAAAAAA/traces.m4:409: ERROR: end of file in string
/usr/bin/m4:/tmp/arAAAAAA/am4tAAAAAA/traces.m4:293: ERROR: end of file in string
unknown channel m4trace:configure.ac:4: -1- m4_pattern_forbid(^_?A[CHUM]_)
m4trace:configure.ac:4: -1- m4_pattern_forbid(_AC_)
m4trace:configure.ac:4: -1- m4_pattern_forbid(^LIBOBJS$, do not use
LIBOBJS directly, use AC_LIBOBJ (see section `AC_LIBOBJ vs LIBOBJS')
m4trace:configure.ac:4: -1- m4_pattern_allow(^AS_FLAGS$)
...
m4trace:configure.ac:4: -1- m4_pattern_allow(^oldincludedir$)
 at /usr/share/autoconf/Autom4te/Channels.pm line 631.
        Autom4te::Channels::msg("m4trace:configure.ac:4: -1-
m4_pattern_forbid(^_?A[CHUM]_)\x{a}m4"..., undef, undef, "partial", 0)
called at /usr/bin/autom4te line 1084
autoreconf: error: /usr/bin/autoconf failed with exit status: 1
dh_autoreconf: error: autoreconf -f -i returned exit code 1
make: *** [debian/rules:7: binary-arch] Error 255
dpkg-buildpackage: error: debian/rules binary-arch subprocess returned
exit status 2
```
Others package like libsigsegv[2] will be failed with almost the same error:
```
m4/sigaltstack-longjmp.m4:13: warning: underquoted definition of
[SV_TRY_LEAVE_HANDLER_LONGJMP
m4/sigaltstack-longjmp.m4:13:   run info Automake 'Extending aclocal'
m4/sigaltstack-longjmp.m4:13:   or see
https://www.gnu.org/software/automake/manual/automake.html#Extending-aclocal
/usr/bin/m4:/tmp/arAAAAAA/am4tAAAAAA/traces.m4:216: ERROR: end of file in string
/usr/bin/m4:/tmp/arAAAAAA/am4tAAAAAA/traces.m4:426: ERROR: end of file in string
/usr/bin/m4:/tmp/arAAAAAA/am4tAAAAAA/traces.m4:311: ERROR: end of file in string
unknown channel m4trace:aclocal.m4:699: -1- AC_SUBST(am__quote)
...
m4trace:configure.ac:20: -1- m4_pattern_allow(^oldincludedir$)
 at /usr/share/autoconf/Autom4te/Channels.pm line 631.
        Autom4te::Channels::msg("m4trace:aclocal.m4:699: -1-
AC_SUBST(am__quote)\x{a}m4trace:acloc"..., undef, undef, "partial", 0)
called at /usr/bin/autom4te line 1084
autoreconf: error: /usr/bin/autoconf failed with exit status: 1
dh_autoreconf: error: autoreconf -f -i returned exit code 1
make: *** [debian/rules:9: binary-arch] Error 255
dpkg-buildpackage: error: debian/rules binary-arch subprocess returned
exit status 2
```
I suspected the issue was raised by automake, but no idea how to confirm it.
So which direction should I debug in? TIA.
(Please ccing me I have trouble to subscribe the mail list, thanks)

BR,
Bo
[0]： https://github.com/yuzibo/riscv32/wiki
[1]: https://salsa.debian.org/debian/dh-exec
[2]: https://salsa.debian.org/common-lisp-team/libsigsegv