Accept any shared library for "libz", not just the static one. Bug#6584
Repetition of the corresponding change, as the 4.1 "acinclude.m4" is not used in 5.0.


config/ac-macros/zlib.m4:
  Accept any shared library for "libz", not just the static one. Bug#6584
  Repetition of the corresponding change, as the 4.1 "acinclude.m4" is not used in 5.0.