autoreconf --install --force broke on files with no timestamps

[Pascal Terjan]

http://git.savannah.gnu.org/gitweb/?p=autoconf.git;a=commit;h=40fa9edce6ad1a05988e4743a7ca64c3a8b3208d
broke many things as it is no longer possible to use autoreconf
--force --install to replace a file with no timestamp.

A lot of install-sh files do not have one.

A few examples:
http://pkgsubmit.mageia.org/autobuild/cauldron/aarch64/core/2020-12-06/rsync-3.2.2-2.mga8.src.rpm/build.0.20201207034825.log
http://pkgsubmit.mageia.org/autobuild/cauldron/aarch64/core/2020-12-06/ruby-2.7.2-33.mga8.src.rpm/build.0.20201208035913.log
http://pkgsubmit.mageia.org/autobuild/cauldron/aarch64/core/2020-12-06/socat-2.0.0-0.b9.9.mga8.src.rpm/build.0.20201207034825.log
http://pkgsubmit.mageia.org/autobuild/cauldron/aarch64/core/2020-12-06/sqlite3-3.34.0-1.mga8.src.rpm/build.0.20201208021354.log

STRERROR_R_CHAR_P broken

[Pascal Terjan]

After 
http://git.savannah.gnu.org/cgit/autoconf.git/commit/lib/autoconf/functions.m4?id=326c9a547423d25c621bc5c0ef76edbf6eda8c92
detection fails because  is no longer included.

checking whether strerror_r is declared... yes
checking whether strerror_r returns char *... no

configure:11444: x86_64-mageia-linux-gnu-gcc -c -O2 -g -pipe -Wformat
-Werror=format-security -Wp,-D_FORTIFY_SOURCE=2 -fstack-protector
--param=ssp-buffer-size=4 -fstack-protector-all
-fasynchronous-unwind-tables -I/usr/include/et -fPIC
-fno-strict-aliasing -fstack-protector-all -I/usr/include/et
conftest.c >&5
conftest.c: In function 'main':
conftest.c:77:14: warning: implicit declaration of function
'strerror_r' [-Wimplicit-function-declaration]
   77 |char x = *strerror_r (0, buf, sizeof buf);
  |  ^~
conftest.c:77:13: error: invalid type argument of unary '*' (have 'int')
   77 |char x = *strerror_r (0, buf, sizeof buf);
  | ^~~~
conftest.c:78:14: warning: initialization of 'char *' from 'int' makes
pointer from integer without a cast [-Wint-conversion]
   78 |char *p = strerror_r (0, buf, sizeof buf);
  |  ^~
configure:11444: $? = 1


The suspicious part of the commit is:

-AC_COMPILE_IFELSE([AC_LANG_PROGRAM([AC_INCLUDES_DEFAULT],
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([],