mostlyclean: also remove .i and .s files

These files will be generated by `make` if CFLAGS contains `-save-temps`
or related flags.

Signed-off-by: Patrick McCarty <patrick.mccarty@intel.com>

.gitignore

@@ -1,5 +1,7 @@
 *~
 *.o
+*.i
+*.s
 .libs/
 *.lo
 *.pc

Makefile.am

@@ -97,6 +97,10 @@ libbsdiff_la_LDFLAGS = \
 	-version-info $(LIBBSDIFF_CURRENT):$(LIBBSDIFF_REVISION):$(LIBBSDIFF_AGE) \
 	-Wl,--version-script=$(top_srcdir)/src/bsdiff.sym
 
+mostlyclean-local:
+	-rm -f *.i
+	-rm -f *.s
+
 distclean-local:
 	-rm -f config.guess~
 	-rm -f config.h.in~