Added obstack.

bootstrap

@@ -78,6 +78,7 @@ human
 lchown
 memset
 modechange
+obstack
 safe-read
 quote
 quotearg

lib/Makefile.am

@@ -99,6 +99,9 @@ libtar_a_SOURCES += lchown.h
 # modechange
 libtar_a_SOURCES += modechange.h modechange.c
 
+# obstack
+libtar_a_SOURCES += obstack.h obstack.c
+
 # pathmax
 libtar_a_SOURCES += pathmax.h