CMake: Add missing iconv dependency

FreeBSD has two iconv systems: It ships an iconv.h itself,
and symbols for that in the libc. But there's also the port
of GNU libiconv, which unfortunately for us, Doxygen depends
on.

This changes things to prefer a separate libiconv library
over the system one; that is, the port on FreeBSD.

Gbp-Dch: ignore

CMake/FindIconv.cmake

@@ -0,0 +1,20 @@
+find_path(ICONV_INCLUDE_DIR NAMES iconv.h)
+
+find_library(ICONV_LIBRARY NAMES iconv)
+if (ICONV_LIBRARY)
+    set(ICONV_SYMBOL_FOUND "${ICONV_LIBRARY}")
+else()
+    check_function_exists(iconv_open ICONV_SYMBOL_FOUND)
+endif()
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(Iconv DEFAULT_MESSAGE ICONV_INCLUDE_DIR ICONV_SYMBOL_FOUND)
+
+if(ICONV_LIBRARY)
+    set(ICONV_LIBRARIES "${ICONV_LIBRARY}")
+else()
+    set(ICONV_LIBRARIES)
+endif()
+set(ICONV_INCLUDE_DIRS "${ICONV_INCLUDE_DIR}")
+
+mark_as_advanced(ICONV_LIBRARY ICONV_INCLUDE_DIR)

CMakeLists.txt

@@ -29,6 +29,7 @@ include(GNUInstallDirs)
 include(TestBigEndian)
 find_package(Threads)
 find_package(LFS REQUIRED)
+find_package(Iconv REQUIRED)
 
 if(USE_NLS)
   find_package(Intl REQUIRED)

apt-pkg/CMakeLists.txt

@@ -28,14 +28,19 @@ target_include_directories(apt-pkg
                            PRIVATE ${ZLIB_INCLUDE_DIRS}
                                    ${BZIP2_INCLUDE_DIR}
                                    ${LZMA_INCLUDE_DIRS}
-                                   ${LZ4_INCLUDE_DIRS})
+                                   ${LZ4_INCLUDE_DIRS}
+                                   ${ICONV_DIRECTORIES}
+)
+
 target_link_libraries(apt-pkg
                       PRIVATE -lutil ${CMAKE_DL_LIBS} ${RESOLV_LIBRARIES}
                              ${CMAKE_THREAD_LIBS_INIT}
                              ${ZLIB_LIBRARIES}
                              ${BZIP2_LIBRARIES}
                              ${LZMA_LIBRARIES}
-                             ${LZ4_LIBRARIES})
+                             ${LZ4_LIBRARIES}
+                             ${ICONV_LIBRARIES}
+)
 set_target_properties(apt-pkg PROPERTIES VERSION ${MAJOR}.${MINOR})
 set_target_properties(apt-pkg PROPERTIES SOVERSION ${MAJOR})
 add_version_script(apt-pkg)