minizip-ng: Properly use libraries from Externals

This also fixes the CMake build on Windows, since it would fail to find our target defined in Externals and would fall back to trying to redefine it, which produces an error.

CMakeLists.txt

@@ -658,6 +658,13 @@ if(NOT (WIN32 AND _M_ARM_64))
   add_definitions(-DHAS_OPENGL)
 endif()
 
+if(NOT WIN32)
+  if(ANDROID)
+    set(USE_SYSTEM_Iconv OFF)
+  endif()
+  dolphin_find_optional_system_library(Iconv Externals/libiconv 1.14)
+endif()
+
 dolphin_find_optional_system_library(pugixml Externals/pugixml)
 
 dolphin_find_optional_system_library_pkgconfig(ENET libenet>=1.3.18 enet::enet Externals/enet)
@@ -718,15 +725,6 @@ dolphin_find_optional_system_library(MBEDTLS Externals/mbedtls 2.28)
 
 dolphin_find_optional_system_library(CURL Externals/curl)
 
-if(NOT WIN32)
-  if(NOT ANDROID)
-    dolphin_find_optional_system_library(Iconv Externals/libiconv 1.14)
-  else()
-    message(STATUS "Using static iconv from Externals")
-    add_subdirectory(Externals/libiconv EXCLUDE_FROM_ALL)
-  endif()
-endif()
-
 if(NOT ANDROID)
   dolphin_find_optional_system_library(HIDAPI Externals/hidapi)
 endif()