When building local zlib ensure we don't link to any system zlib or minzip.

CMakeLists.txt

@@ -320,6 +320,8 @@ IF( NOT ZLIB_FOUND )
   SET(ZLIB_FOUND 1)
   SET(ZLIB_LIBRARIES zlibstatic)
   SET(ZLIB_INCLUDE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/contrib/zlib ${CMAKE_CURRENT_BINARY_DIR}/contrib/zlib)
+  # need to ensure we don't link with system zlib or minizip as well.
+  SET(ASSIMP_BUILD_MINIZIP 1)
 ELSE(NOT ZLIB_FOUND)
   ADD_DEFINITIONS(-DASSIMP_BUILD_NO_OWN_ZLIB)
   SET(ZLIB_LIBRARIES_LINKED -lz)
@@ -327,7 +329,9 @@ ENDIF(NOT ZLIB_FOUND)
 INCLUDE_DIRECTORIES(${ZLIB_INCLUDE_DIR})
 
 # Search for unzip
-use_pkgconfig(UNZIP minizip)
+IF( NOT ASSIMP_BUILD_MINIZIP )
+  use_pkgconfig(UNZIP minizip)
+ENDIF( NOT ASSIMP_BUILD_MINIZIP )
 
 IF ( ASSIMP_NO_EXPORT )
   ADD_DEFINITIONS( -DASSIMP_BUILD_NO_EXPORT)