Export library directory and shared libs to CMake config (#1113)

This pull request adds two new exported variables to the CMake config:

YAML_CPP_LIBRARY_DIR - points to the directory containing the built library files
YAML_CPP_SHARED_LIBS_BUILT - boolean value, lets users know whether shared libraries were built or not

CMakeLists.txt

@@ -153,7 +153,7 @@ configure_package_config_file(
   "${PROJECT_SOURCE_DIR}/yaml-cpp-config.cmake.in"
   "${PROJECT_BINARY_DIR}/yaml-cpp-config.cmake"
   INSTALL_DESTINATION "${CONFIG_EXPORT_DIR}"
-  PATH_VARS CMAKE_INSTALL_INCLUDEDIR CONFIG_EXPORT_DIR)
+  PATH_VARS CMAKE_INSTALL_INCLUDEDIR CMAKE_INSTALL_LIBDIR CONFIG_EXPORT_DIR YAML_BUILD_SHARED_LIBS)
 unset(EXPORT_TARGETS)
 
 write_basic_package_version_file(

yaml-cpp-config.cmake.in

 # - Config file for the yaml-cpp package
 # It defines the following variables
 #  YAML_CPP_INCLUDE_DIR       - include directory
+#  YAML_CPP_LIBRARY_DIR       - directory containing libraries
+#  YAML_CPP_SHARED_LIBS_BUILT - whether we have built shared libraries or not
 #  YAML_CPP_LIBRARIES         - libraries to link against
 
 @PACKAGE_INIT@
 
 set_and_check(YAML_CPP_INCLUDE_DIR "@PACKAGE_CMAKE_INSTALL_INCLUDEDIR@")
+set_and_check(YAML_CPP_LIBRARY_DIR "@PACKAGE_CMAKE_INSTALL_LIBDIR@")
+
+# Are we building shared libraries?
+set(YAML_CPP_SHARED_LIBS_BUILT "@PACKAGE_YAML_BUILD_SHARED_LIBS@")
 
 # Our library dependencies (contains definitions for IMPORTED targets)
 include(@PACKAGE_CONFIG_EXPORT_DIR@/yaml-cpp-targets.cmake)