tools/coreutils: bootstrap to local gnulib source

Using the local gnulib source during bootstrap
allows for fine-grained control over the macros
and source files for use with coreutils
but part of gnulib instead of coreutils,
without having to wait for a release
or deal with gnulib as a git submodule.

In this case, the execution of autotools
must be skipped by force.
Autoconf and Automake during bootstrap on coreutils
only works right when using directly checked-out source.

There is a symbol in gnulib, @GNULIB_TIME@
that is not yet defined in coreutils source,
so we use the backup of lib/time.in.h instead
of the one provided by gnulib source.

Signed-off-by: Michael Pratt <mcpratt@pm.me>

tools/coreutils/patches/000-bootstrap.patch

@@ -0,0 +1,45 @@
+--- a/bootstrap
++++ b/bootstrap
+@@ -278,7 +278,7 @@ check_exists() {
+       ($2 --version </dev/null)
+     fi
+   else
+-    ($1 --version </dev/null) >/dev/null 2>&1
++    ($@ --version </dev/null) >/dev/null 2>&1
+   fi
+ 
+   test $? -lt 126
+@@ -563,7 +563,7 @@ p
+ q'
+ 
+ get_version() {
+-  app=$1
++  app="$@"
+ 
+   $app --version >/dev/null 2>&1 || { $app --version; return 1; }
+ 
+@@ -620,13 +620,13 @@ check_versions() {
+     if [ "$req_ver" = "-" ]; then
+       # Merely require app to exist; not all prereq apps are well-behaved
+       # so we have to rely on $? rather than get_version.
+-      if ! check_exists --verbose $app; then
++      if ! check_exists --verbose "$app"; then
+         warn_ "Error: '$app' not found"
+         ret=1
+       fi
+     else
+       # Require app to produce a new enough version string.
+-      inst_ver=$(get_version $app)
++      inst_ver=$(get_version "$app")
+       if [ ! "$inst_ver" ]; then
+         warn_ "Error: '$app' not found"
+         ret=1
+@@ -923,7 +923,7 @@ version_controlled_file() {
+ # two just-pre-run programs.
+ 
+ # Import from gettext.
+-with_gettext=yes
++with_gettext=no
+ grep '^[	 ]*AM_GNU_GETTEXT_VERSION(' configure.ac >/dev/null || \
+     with_gettext=no
+