externalsrc: remove nostamp from do_configure

Extend the srctree_hash_files() function in externalsrc.bbclass to
handle non-Git source trees.  If the source tree is not a git
repository, srctree_hash_files() now simply adds the whole source tree
as a dependency, causing bitbake to basically hash every file in it.
Hidden files and directories in the source tree root are ignored by the
glob currently used. This has the advantage of automatically ignoring
.git directory, for example.

During the first bitbake run preparing of the task runqueue may take
much longer if the source tree is not a git repository. The reason is
that all the files in the source tree are hashed.  Subsequent builds are
not significantly slower because (most) file hashes are found from the
cache.

[YOCTO #8853]

(From OE-Core rev: a797abe08bfe4144e120c984d1718c2cc3d87c0a)

Signed-off-by: Markus Lehtonen <markus.lehtonen@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/externalsrc.bbclass

@@ -149,5 +149,5 @@ def srctree_hash_files(d):
             fobj.write(sha1)
         ret = oe_hash_file + ':True'
     else:
-        d.setVarFlag('do_compile', 'nostamp', '1')
+        ret = d.getVar('EXTERNALSRC', True) + '/*:True'
     return ret