fix(build): link math library for unit tests

CMakeLists.txt

@@ -19,6 +19,11 @@ set(IKV_SOURCES
     src/loaders/ikv2.c
 )
 
+set(IKV_MATH_LIBRARIES)
+if(UNIX AND NOT APPLE)
+    list(APPEND IKV_MATH_LIBRARIES m)
+endif()
+
 add_library(ikv_obj OBJECT ${IKV_SOURCES})
 target_include_directories(ikv_obj
     PUBLIC
@@ -58,7 +63,7 @@ if(IKV_BUILD_DEMOS)
     target_link_libraries(ikv_demo PRIVATE ikv)
 
     add_executable(ikv_unit_test demo/unit_test.c)
-    target_link_libraries(ikv_unit_test PRIVATE ikv)
+    target_link_libraries(ikv_unit_test PRIVATE ikv ${IKV_MATH_LIBRARIES})
 endif()
 
 if(IKV_BUILD_TESTS)
@@ -75,6 +80,7 @@ if(IKV_BUILD_TESTS)
             ${CMAKE_CURRENT_SOURCE_DIR}/src
     )
     target_compile_features(ikv_tests PRIVATE c_std_99)
+    target_link_libraries(ikv_tests PRIVATE ${IKV_MATH_LIBRARIES})
 
     file(STRINGS "${CMAKE_CURRENT_SOURCE_DIR}/demo/unit_test.c" IKV_TEST_CASE_ROWS
         REGEX "^    \\{\"[^\"]+\", test_[^}]+\\},?$"