[SV 54161] Fix second expansion of $* for paths

If the stem matches a path containing a directory not just a
filename, make sure the second expansion of $* in the
prerequisites matches $* in the recipe.  This requires using
$(*F) when replacing % in the first expansion to preserve the
simple filename.

* src/implicit.c (pattern_search): If lastslash is set prepend
the directory onto the stem.  Then use $(*F) when expanding %.
* tests/scripts/features/se_implicit: Add a test case

tests/scripts/features/se_implicit

@@ -254,5 +254,13 @@ foo: $$(info $$<)
 !,
               '', "bar\n#MAKE#: Nothing to be done for 'foo'.\n");
 
+# SV 54161: Expand $$* properly when it contains a path
+
+run_make_test(q!
+.SECONDEXPANSION:
+%x: $$(info $$*); @echo '$*'
+!,
+              'q/ux', "q/u\nq/u\n");
+
 # This tells the test driver that the perl test script executed properly.
 1;