Merge pull request libgit2#3796 from mmuman/haiku

Preliminary Haiku port

Author: Edward Thomson

CMakeLists.txt

@@ -151,6 +151,10 @@ FUNCTION(TARGET_OS_LIBRARIES target)
 		TARGET_LINK_LIBRARIES(${target} socket nsl)
 		LIST(APPEND LIBGIT2_PC_LIBS "-lsocket" "-lnsl")
 		SET(LIBGIT2_PC_LIBS ${LIBGIT2_PC_LIBS} PARENT_SCOPE)
+	ELSEIF(CMAKE_SYSTEM_NAME MATCHES "Haiku")
+		TARGET_LINK_LIBRARIES(${target} network)
+		LIST(APPEND LIBGIT2_PC_LIBS "-lnetwork")
+		SET(LIBGIT2_PC_LIBS ${LIBGIT2_PC_LIBS} PARENT_SCOPE)
 	ENDIF()
 	CHECK_LIBRARY_EXISTS(rt clock_gettime "time.h" NEED_LIBRT)
 	IF(NEED_LIBRT)