Revert "Replace sed trickery in the gcc dependency generation command"

This made dependencies entirely non-functional, and also the syntax is
not supported by gcc 2.95.

Originally committed as revision 15607 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -1012,9 +1012,8 @@ SLIBNAME_WITH_VERSION='$(SLIBNAME).$(LIBVERSION)'
 SLIBNAME_WITH_MAJOR='$(SLIBNAME).$(LIBMAJOR)'
 LIB_INSTALL_EXTRA_CMD='$(RANLIB) "$(LIBDIR)/$(LIBNAME)"'
 
-# gcc stupidly only outputs the basename of targets with -MM, but we need the
-# full relative path for objects in subdirectories for non-recursive Make.
-DEPEND_CMD='$(CC) $(CFLAGS) -MM -MG -MT $@ $<'
+# gcc stupidly only outputs the basename of targets with -MM
+DEPEND_CMD='$(CC) $(CFLAGS) -MM -MG $< | sed -e "/^\#.*/d" -e "1s,^,$(@D)/," -e "s,\\([[:space:]]\\)\\(version\\.h\\),\\1\$$(BUILD_ROOT_REL)/\\2,"'
 
 # find source path
 source_path="`dirname \"$0\"`"