[PATCH] Fallback check for zlib

[Xīcò]

Added the fallback check for zlib. Tested on FreeBSD stable/10.
C test checks for major zlib compatibility (see zlib doc/examples).

Xīcò (1):
  Fallback check for zlib.

 compat/have_zlib.c |  6 ++++++
 configure          | 21 ++++++++++++++++-----
 2 files changed, 22 insertions(+), 5 deletions(-)
 create mode 100644 compat/have_zlib.c

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1.9.2