gdb/testsuite/: garbage collect a few references to dead targets

gdb/testsuite/: garbage collect a few references to dead targets

gdb/testsuite/ChangeLog:
2015-08-24  Pedro Alves  <palves@redhat.com>

	* config/m32r-stub.exp: Remove file.
	* gdb.base/call-ar-st.exp: Remove reference to sparclet.
	* gdb.base/call-rt-st.exp: Likewise.
	* gdb.base/call-strs.exp: Likewise.
	* gdb.base/default.exp: Remove references to h8300-*-hms and
	*-*-udi*.
	* gdb.base/funcargs.exp: Remove reference to sparclet-*-*.