pc: Put libcurl and libssh2 in Libs.private

Pass on to whoever wants to link to libgit2 statically the flags that we
would have used for these libraries.

Putting them in Requires.private as we do now makes pkg-config put their
dependencies in the linker arguments as well, which is not what we want.

CMakeLists.txt

@@ -201,7 +201,7 @@ IF (WIN32 AND WINHTTP)
 	LINK_LIBRARIES(winhttp rpcrt4 crypt32)
 ELSE ()
 	IF (CURL)
-		FIND_PACKAGE(CURL)
+		PKG_CHECK_MODULES(CURL libcurl)
 	ENDIF ()
 
 	IF (NOT AMIGA AND USE_OPENSSL)
@@ -212,7 +212,7 @@ ELSE ()
 		ADD_DEFINITIONS(-DGIT_CURL)
 		INCLUDE_DIRECTORIES(${CURL_INCLUDE_DIRS})
 		LINK_LIBRARIES(${CURL_LIBRARIES})
-		SET(LIBGIT2_PC_REQUIRES "${LIBGIT2_PC_REQUIRES} libcurl")
+		SET(LIBGIT2_PC_LIBS "${LIBGIT2_PC_LIBS} ${CURL_LDFLAGS}")
 	ENDIF()
 
 	FIND_PACKAGE(HTTP_Parser)
@@ -280,7 +280,7 @@ IF (LIBSSH2_FOUND)
 	ADD_DEFINITIONS(-DGIT_SSH)
 	INCLUDE_DIRECTORIES(${LIBSSH2_INCLUDE_DIRS})
 	LINK_DIRECTORIES(${LIBSSH2_LIBRARY_DIRS})
-	SET(LIBGIT2_PC_REQUIRES "${LIBGIT2_PC_REQUIRES} libssh2")
+	SET(LIBGIT2_PC_LIBS "${LIBGIT2_PC_LIBS} ${LIBSSH2_LDFLAGS}")
 	SET(SSH_LIBRARIES ${LIBSSH2_LIBRARIES})
 
 	CHECK_LIBRARY_EXISTS("${LIBSSH2_LIBRARIES}" libssh2_userauth_publickey_frommemory "" HAVE_LIBSSH2_MEMORY_CREDENTIALS)