Don't use properties when setting FMT_LIB_NAME

CMakeLists.txt

@@ -198,12 +198,12 @@ target_include_directories(fmt PUBLIC
 set(FMT_DEBUG_POSTFIX d CACHE STRING "Debug library postfix.")
 
 set_target_properties(fmt PROPERTIES
-  OUTPUT_NAME "fmt"
   VERSION ${FMT_VERSION} SOVERSION ${CPACK_PACKAGE_VERSION_MAJOR}
   DEBUG_POSTFIX "${FMT_DEBUG_POSTFIX}")
 
-# Set FMT_LIB_NAME for pkg-config fmt.pc.
-get_target_property(FMT_LIB_NAME fmt OUTPUT_NAME)
+# Set FMT_LIB_NAME for pkg-config fmt.pc. We cannot use the OUTPUT_NAME target
+# property because it's not set by default.
+set(FMT_LIB_NAME fmt)
 if (CMAKE_BUILD_TYPE STREQUAL "Debug")
   set(FMT_LIB_NAME ${FMT_LIB_NAME}${FMT_DEBUG_POSTFIX})
 endif ()