Make sure installed glm::glm has the includes

CMakeLists.txt

@@ -22,7 +22,6 @@ add_library(glm::glm ALIAS glm)
 if(${CMAKE_SOURCE_DIR} STREQUAL ${CMAKE_CURRENT_SOURCE_DIR})
 
 	include(CPack)
-	include(GNUInstallDirs)
 	install(DIRECTORY glm DESTINATION ${CMAKE_INSTALL_INCLUDEDIR} PATTERN "CMakeLists.txt" EXCLUDE)
 	install(EXPORT glm FILE glmConfig.cmake DESTINATION ${CMAKE_INSTALL_LIBDIR}/cmake/glm NAMESPACE glm::)
 	include(CMakePackageConfigHelpers)

glm/CMakeLists.txt

@@ -44,6 +44,8 @@ source_group("SIMD Files" FILES ${SIMD_HEADER})
 
 add_library(glm INTERFACE)
 
+include(GNUInstallDirs)
+
 target_include_directories(glm INTERFACE
 	$<BUILD_INTERFACE:${CMAKE_SOURCE_DIR}>
 	$<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}>