bug#21956: subdir-objecs dies with "rm: cannot remove 'emxp_cm_bl': Is a directory", even git version

[Joakim Tjernlund]

automake>= 1.13 (did not test lower than that) dies during make with:
 CCLD     emxp_cm_bl_shell
 rm: cannot remove 'emxp_cm_bl': Is a directory
 Makefile:1070: recipe for target 'emxp_cm_bl' failed

This happens if you have the same name on the containing directory and
in bin_PROGRAMS, like so
  bin_PROGRAMS = emxp_hw_bl
  emxp_hw_bl_SOURCES = emxp_hw_bl/emxp_hw_bl.c

Here is the offending Makefile snippet:
emxp_hw_bl$(EXEEXT): $(emxp_hw_bl_OBJECTS) $(emxp_hw_bl_DEPENDENCIES) 
$(EXTRA_emxp_hw_bl_DEPENDENCIES) 
        rm -f emxp_hw_bl$(EXEEXT)
        $(AM_V_CCLD)$(emxp_hw_bl_LINK) $(emxp_hw_bl_OBJECTS) 
$(emxp_hw_bl_LDADD) $(LIBS)