configure: remove extra backslashes from suncc DEPEND_CMD

Patch by Michael Kostylev <michael kostylev gmail>

Originally committed as revision 20428 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -1617,7 +1617,7 @@ elif $cc -v 2>&1 | grep -q clang; then
 elif $cc -V 2>&1 | grep -q Sun; then
     cc_type=suncc
     cc_version="AV_STRINGIFY(__SUNPRO_C)"
-    DEPEND_CMD='$(DEPCC) $(DEPFLAGS) $< | sed -e "1s,^.*: ,$@: ," -e "\$$!s,\$$, \\\\\\," -e "1!s,^.*: , ," > $(@:.o=.d)'
+    DEPEND_CMD='$(DEPCC) $(DEPFLAGS) $< | sed -e "1s,^.*: ,$@: ," -e "\$$!s,\$$, \\\," -e "1!s,^.*: , ," > $(@:.o=.d)'
     DEPFLAGS='$(CPPFLAGS) $(CFLAGS) -xM1'
 fi