Try not linking with absl_check

src/CMakeLists.txt

@@ -25,9 +25,6 @@ add_library(adakCore
     GeometricDisconnect.cpp
     SystemClock.cpp)
 
-# Abseil appears to require gmock
-find_package(GTest REQUIRED)
-
 # Newer versions of protobuf require abseil
 find_package(absl REQUIRED)
 
@@ -37,7 +34,12 @@ target_include_directories(adakCore PUBLIC ${PROJECT_SOURCE_DIR}/include)
 add_executable(adak main.cpp ../include/config.hpp)
 target_include_directories(adak PRIVATE ${PROJECT_SOURCE_DIR}/include)
 
-set(COMMON_LIBRARIES adakCore messages absl::absl_check)
+if (APPLE)
+    set(COMMON_LIBRARIES adakCore messages absl::absl_check)
+else()
+    set(COMMON_LIBRARIES adakCore messages)
+endif()
+
 # Determine whether we need to add stdc++fs.
 # Inspired by https://stackoverflow.com/questions/54290254/problem-adding-stdfilesystem-to-cmake-project
 try_compile(HAS_FS "${CMAKE_BINARY_DIR}/temp"