Restore the old behavior when using gzip

Commit b2f454b ("Add option to control keymaps compression") removed -n
option from gzip invocation, the absence of which makes gzip write file
timestamps into compressed .gz files. These timestamps vary from one
build to another, and so the resulting installed .gz files are
non-reproducible.

Since not all archivers understand this option it is impossible to add
it for all archivers by default.

But we can bring back the default behavior (the case where no configure
options were specified) by using “gzip -n” as the archiver.

Link: #124
Fixes: b2f454b ("Add option to control keymaps compression")
Signed-off-by: Alexey Gladkov <[email protected]>

configure.ac

@@ -188,8 +188,8 @@ AC_ARG_ENABLE(compress,
 	[enable_compress=$enableval], [enable_compress=auto])
 
 AS_IF([test "x$enable_compress" = xno],   [],
-      [test "x$enable_compress" = xyes],  [AC_CHECK_PROGS([COMPRESS_PROG], [zstd xz bzip2 gzip])],
-      [test "x$enable_compress" = xauto], [AC_CHECK_PROGS([COMPRESS_PROG], [gzip])],
+      [test "x$enable_compress" = xyes],  [AC_CHECK_PROGS([COMPRESS_PROG], [zstd xz bzip2 "gzip -n"])],
+      [test "x$enable_compress" = xauto], [AC_CHECK_PROGS([COMPRESS_PROG], ["gzip -n"])],
       [AC_CHECK_PROGS([COMPRESS_PROG], ["$enable_compress"])])
 AM_CONDITIONAL(ENABLE_COMPRESS, test "x$COMPRESS_PROG" != "x")