CMake: Use find_package and imported targets for Iconv

Fixes us forgetting to add its include directories, which could result in linking to a dylib from MacPorts while using the system's header, and failing to link because they use different function names

CMakeLists.txt

@@ -914,19 +914,16 @@ else()
   include_directories(BEFORE Externals/curl/include)
 endif()
 
-if (NOT ANDROID)
-  find_library(ICONV_LIBRARIES NAMES iconv libiconv libiconv-2 c)
-  find_path(ICONV_INCLUDE_DIR NAMES iconv.h)
+if(NOT ANDROID)
+  find_package(Iconv)
 endif()
 
-if (NOT ANDROID AND ICONV_LIBRARIES AND ICONV_INCLUDE_DIR)
-  mark_as_advanced(ICONV_INCLUDE_DIR ICONV_LIBRARIES)
+if(TARGET Iconv::Iconv)
+  message(STATUS "Using shared iconv")
 else()
   check_vendoring_approved(iconv)
   message(STATUS "Using static iconv from Externals")
-  include_directories(Externals/libiconv-1.14/include)
   add_subdirectory(Externals/libiconv-1.14)
-  set(ICONV_LIBRARIES iconv)
 endif()
 
 if(NOT ANDROID)

Externals/libiconv-1.14/CMakeLists.txt

@@ -1,10 +1,13 @@
-include_directories(include)
-include_directories(libcharset/include)
-
-set(SRCS	lib/iconv.c
-		lib/relocatable.c
-		libcharset/lib/localcharset.c
+add_library(iconv STATIC
+	lib/iconv.c
+	lib/relocatable.c
+	libcharset/lib/localcharset.c
+)
+target_include_directories(iconv
+	PUBLIC
+		include
+	PRIVATE
+		libcharset/include
 )
-
-add_library(iconv STATIC ${SRCS})
 dolphin_disable_warnings_msvc(iconv)
+add_library(Iconv::Iconv ALIAS iconv)

Source/Core/Common/CMakeLists.txt

@@ -156,7 +156,7 @@ PUBLIC
 PRIVATE
   ${CURL_LIBRARIES}
   FatFs
-  ${ICONV_LIBRARIES}
+  Iconv::Iconv
   ${spng_target}
   ${VTUNE_LIBRARIES}
 )