build: Always check for gzip/bzip2/xz.

This allows (guix config) to contain valid values of %GZIP et al. even
when configured with --disable-daemon.

* config-daemon.ac: Move 'AC_PATH_PROG' invocations for
gzip & co. to...
* configure.ac: ... here.

config-daemon.ac

@@ -14,14 +14,6 @@ if test "x$guix_build_daemon" = "xyes"; then
   AC_PROG_RANLIB
   AC_CONFIG_HEADER([nix/config.h])
 
-  dnl Decompressors, for use by the substituter.
-  AC_PATH_PROG([GZIP], [gzip])
-  AC_PATH_PROG([BZIP2], [bzip2])
-  AC_PATH_PROG([XZ], [xz])
-  AC_SUBST([GZIP])
-  AC_SUBST([BZIP2])
-  AC_SUBST([XZ])
-
   dnl Use 64-bit file system calls so that we can support files > 2 GiB.
   AC_SYS_LARGEFILE
 

configure.ac

@@ -90,6 +90,14 @@ GUIX_CHECK_LIBC_MOUNT
 AM_CONDITIONAL([BUILD_SYSCALLS_MODULE],
   [test "x$guix_cv_libc_has_mount" = "xyes"])
 
+dnl Decompressors, for use by the substituter and other modules.
+AC_PATH_PROG([GZIP], [gzip])
+AC_PATH_PROG([BZIP2], [bzip2])
+AC_PATH_PROG([XZ], [xz])
+AC_SUBST([GZIP])
+AC_SUBST([BZIP2])
+AC_SUBST([XZ])
+
 AC_ARG_WITH([nix-prefix],
   [AS_HELP_STRING([--with-nix-prefix=DIR],
     [search for Nix in DIR (for testing purposes and '--disable-daemon' builds)])],