Fix install (#879)

* Fix default installation path

* Fixup previous commit.
This makes the install location not correct for Debian and similar linux distro, but upstream don't plan to change "lib/cpprestsdk" location,
so at least we can override the location with -DCPPREST_EXPORT_DIR=cmake and keep the CMAKE_INSTALL_LIBDIR multiarch location

Release/CMakeLists.txt

@@ -18,7 +18,7 @@ enable_testing()
 set(WERROR ON CACHE BOOL "Treat Warnings as Errors.")
 set(CPPREST_EXCLUDE_WEBSOCKETS OFF CACHE BOOL "Exclude websockets functionality.")
 set(CPPREST_EXCLUDE_COMPRESSION OFF CACHE BOOL "Exclude compression functionality.")
-set(CPPREST_EXPORT_DIR lib/cpprestsdk CACHE STRING "Directory to install CMake config files.")
+set(CPPREST_EXPORT_DIR cpprestsdk CACHE STRING "Directory to install CMake config files.")
 set(CPPREST_INSTALL_HEADERS ON CACHE BOOL "Install header files.")
 set(CPPREST_INSTALL ON CACHE BOOL "Add install commands.")
 

Release/src/CMakeLists.txt

@@ -262,12 +262,12 @@ if(CPPREST_INSTALL)
 
   install(
     FILES "${CMAKE_CURRENT_BINARY_DIR}/cpprestsdk-config.cmake"
-    DESTINATION ${CPPREST_EXPORT_DIR}
+    DESTINATION ${CMAKE_INSTALL_LIBDIR}/${CPPREST_EXPORT_DIR}
   )
   install(
     EXPORT cpprestsdk-targets
     FILE cpprestsdk-targets.cmake
     NAMESPACE cpprestsdk::
-    DESTINATION ${CPPREST_EXPORT_DIR}
+    DESTINATION ${CMAKE_INSTALL_LIBDIR}/${CPPREST_EXPORT_DIR}
   )
 endif()