Build both a static and a shared version of zlib with cmake.

CMakeLists.txt

@@ -9,10 +9,6 @@ set(INSTALL_INC_DIR "${CMAKE_INSTALL_PREFIX}/include" CACHE PATH "Installation d
 set(INSTALL_MAN_DIR "${CMAKE_INSTALL_PREFIX}/share/man" CACHE PATH "Installation directory for manual pages")
 set(INSTALL_PKGCONFIG_DIR "${CMAKE_INSTALL_PREFIX}/share/pkgconfig" CACHE PATH "Installation directory for pkgconfig (.pc) files")
 
-if(NOT DEFINED BUILD_SHARED_LIBS)
-    option(BUILD_SHARED_LIBS "Build a shared library form of zlib" ON)
-endif()
-
 include(CheckTypeSize)
 include(CheckFunctionExists)
 include(CheckIncludeFile)
@@ -147,9 +143,9 @@ if(MINGW)
     set(ZLIB_SRCS ${ZLIB_SRCS} ${CMAKE_CURRENT_BINARY_DIR}/zlib1rc.obj)
 endif(MINGW)
 
-add_library(zlib ${ZLIB_SRCS} ${ZLIB_PUBLIC_HDRS} ${ZLIB_PRIVATE_HDRS})
+add_library(zlib SHARED ${ZLIB_SRCS} ${ZLIB_PUBLIC_HDRS} ${ZLIB_PRIVATE_HDRS})
+add_library(zlibstatic STATIC ${ZLIB_SRCS} ${ZLIB_PUBLIC_HDRS} ${ZLIB_PRIVATE_HDRS})
 set_target_properties(zlib PROPERTIES DEFINE_SYMBOL ZLIB_DLL)
-
 set_target_properties(zlib PROPERTIES SOVERSION 1)
 
 if(NOT CYGWIN)
@@ -165,14 +161,14 @@ endif()
 
 if(UNIX)
     # On unix-like platforms the library is almost always called libz
-   set_target_properties(zlib PROPERTIES OUTPUT_NAME z)
+   set_target_properties(zlib zlibstatic PROPERTIES OUTPUT_NAME z)
 elseif(BUILD_SHARED_LIBS AND WIN32)
     # Creates zlib1.dll when building shared library version
     set_target_properties(zlib PROPERTIES SUFFIX "1.dll")
 endif()
 
 if(NOT SKIP_INSTALL_LIBRARIES AND NOT SKIP_INSTALL_ALL )
-    install(TARGETS zlib
+    install(TARGETS zlib zlibstatic
         RUNTIME DESTINATION "${INSTALL_BIN_DIR}"
         ARCHIVE DESTINATION "${INSTALL_LIB_DIR}"
         LIBRARY DESTINATION "${INSTALL_LIB_DIR}" )