Fix build with non-OpenSSL SSL-enabled backends

Qt 5.4 introduced the ability to split out the OpenSSL-specific parts
of SSL, so allow users of this configuration to still build the SSL
server.

Change-Id: I03e446c1c0fa4062afe16e58d1b7a80373da12a6
Reviewed-by: Maurice Kalinowski <maurice.kalinowski@digia.com>

src/websockets/websockets.pro

@@ -40,7 +40,7 @@ SOURCES += \
     $$PWD/qmaskgenerator.cpp \
     $$PWD/qdefaultmaskgenerator_p.cpp
 
-contains(QT_CONFIG, openssl) | contains(QT_CONFIG, openssl-linked) {
+contains(QT_CONFIG, ssl) | contains(QT_CONFIG, openssl) | contains(QT_CONFIG, openssl-linked) {
     SOURCES += $$PWD/qsslserver.cpp
     PRIVATE_HEADERS += $$PWD/qsslserver_p.h
 }