check for bfd_uncompress_section_contents instead of bfd_init, because

the former will fail if libbfd is a static library and has a libz
dependency that we don't know about (#3756)

configure.ac

@@ -782,7 +782,7 @@ fi
 dnl ** check whether this machine has BFD and liberty installed (used for debugging)
 dnl    the order of these tests matters: bfd needs liberty
 AC_CHECK_LIB(iberty, xmalloc)
-AC_CHECK_LIB(bfd,    bfd_init)
+AC_CHECK_LIB(bfd,    bfd_uncompress_section_contents)
 
 dnl ################################################################
 dnl Check for libraries