bootstrap: use $gnulib_clone_since

* bootstrap.conf: Add $gnulib_clone_since.
* gl-mod/bootstrap: Update to the latest git hash.
* bootstrap: Regenerate.

bootstrap

@@ -160,6 +160,9 @@ gnulib_non_module_files="
 gnulib_path=
 gnulib_url=
 
+# Date from which to clone github, to avoid a full clone.
+gnulib_clone_since=
+
 # Additional gnulib-tool options to use.
 gnulib_tool_options="
         --no-changelog
@@ -2822,7 +2825,7 @@ test extract-trace = "$progname" && func_main "$@"
 # End:
 
 # Set a version string for *this* script.
-scriptversion=2019-02-19.15; # UTC
+scriptversion=2019-03-22.11; # UTC
 
 
 ## ------------------- ##
@@ -4217,8 +4220,9 @@ func_require_gnulib_submodule ()
         trap func_cleanup_gnulib 1 2 13 15
 
         shallow=
-        $GIT clone -h 2>&1 |func_grep_q -- --depth \
-            && shallow='--depth 365'
+        test -n "$gnulib_clone_since" && \
+            $GIT clone -h 2>&1 |func_grep_q -- --shallow-since \
+            && shallow="--shallow-since=$gnulib_clone_since"
 
         func_show_eval "$GIT clone $shallow '$gnulib_url' '$gnulib_path'" \
           func_cleanup_gnulib

bootstrap.conf

@@ -56,6 +56,9 @@ buildreq_readme=HACKING
 # Non-default gnulib directories.
 local_gl_path=gl:gl-mod/bootstrap
 
+# We don't need the whole copy of gnulib.
+gnulib_clone_since=2019-02-19
+
 # Additional gnulib-tool options to use.
 gnulib_tool_options=$gnulib_tool_options"
         --avoid=dummy

gl-mod/bootstrap

@@ -1 +1 @@
-Subproject commit 41a7749cb825ab2d58969087e3b25a2d3632a01b
+Subproject commit 037f83765b6e8f90dfabdfac4889be22a5a3f4a4