ZOOKEEPER-3017: Link libm in CMake on FreeBSD.

andschwa

Per your suggestion here: https://reviews.apache.org/r/66384/

Author: David Forsythe <dforsyth@freebsd.org>

Reviewers: Andrew Schwartzmeyer <andrew@schwartzmeyer.com>, Andor Molnár <andor@cloudera.com>, Michael Han <hanm@apache.org>

Closes #499 from dforsyth/ZOOKEEPER-3017

src/c/CMakeLists.txt

@@ -154,7 +154,7 @@ configure_file(cmake_config.h.in ${CMAKE_SOURCE_DIR}/include/config.h)
 # hashtable library
 set(hashtable_sources src/hashtable/hashtable_itr.c src/hashtable/hashtable.c)
 add_library(hashtable STATIC ${hashtable_sources})
-target_link_libraries(hashtable PUBLIC $<$<PLATFORM_ID:Linux>:m>)
+target_link_libraries(hashtable PUBLIC $<$<OR:$<PLATFORM_ID:Linux>,$<PLATFORM_ID:FreeBSD>>:m>)
 
 # zookeeper library
 set(zookeeper_sources