Fixed cxxanyargs/depend

* Removed excess backslashes
* Fixed the target name to try failure.cpp

ext/-test-/cxxanyargs/depend

@@ -1,9 +1,9 @@
-$(DLLIB) $(STATIC_LIB): failure.failed
+$(TARGET_SO) $(STATIC_LIB): failure.failed
 
 failure.failed: failure.cpp cxxanyargs.o
-	$(Q)$(RUBY) -rfileutils \\
-	  -e "err = IO.popen(%[$(MAKE) failure.o], err:[:child, :out], &:read)" \\
-	  -e "abort err unless /rb_define_method/ =~ err" \\
+	$(Q)$(RUBY) -rfileutils \
+	  -e "err = IO.popen(%[$(MAKE) failure.o], err:[:child, :out], &:read)" \
+	  -e "abort err unless /rb_define_method/ =~ err" \
 	  -e "FileUtils.touch(*ARGV)" $@
 
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