Description: catch linker warnings in some config tests
 Without this, qmake wrongly thinks that the tests succeed, for example:
 .
 ./config.tests/unix/futimens/futimens.cpp:44: warning: futimens is not implemented and will always fail
 test config.corelib.tests.futimens succeeded
Author: Dmitry Shachnev <mitya57@debian.org>
Forwarded: https://codereview.qt-project.org/163214 (rejected)
Bug: https://bugs.debian.org/827935
Last-Update: 2017-12-07

--- a/config.tests/unix/futimens/futimens.pro
+++ b/config.tests/unix/futimens/futimens.pro
@@ -4,3 +4,4 @@ SOURCES += futimens.cpp
 # targets. This simplifies the logic at the call site dramatically, as it isn't
 # strictly needed compared to futimes().
 darwin: QMAKE_CXXFLAGS += -Werror=unguarded-availability
+QMAKE_LFLAGS += -Wl,--fatal-warnings
--- a/config.tests/unix/getentropy/getentropy.pro
+++ b/config.tests/unix/getentropy/getentropy.pro
@@ -1 +1,2 @@
 SOURCES = getentropy.cpp
+QMAKE_LFLAGS += -Wl,--fatal-warnings
--- a/src/corelib/configure.json
+++ b/src/corelib/configure.json
@@ -254,6 +254,7 @@
             "label": "O_CLOEXEC",
             "type": "compile",
             "test": {
+                "qmake": "QMAKE_LFLAGS += -Wl,--fatal-warnings",
                 "head": "#define _GNU_SOURCE 1",
                 "include": [ "sys/types.h", "sys/socket.h", "fcntl.h", "unistd.h" ],
                 "main": [