Debugger: Remove one (and only) use of QProcess::systemEnvironment

This is not recommended to use, and using Environment::systemEnvironment()
also saves a conversion.

Change-Id: I7af24a5bbf432617a75421e6950292acc4b529a3
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/plugins/debugger/gdb/gdbengine.cpp

@@ -4975,7 +4975,7 @@ CoreInfo CoreInfo::readExecutableNameFromCore(const Runnable &debugger, const QS
     args += {"-ex", "core " + coreFile};
 
     SynchronousProcess proc;
-    Environment envLang(QProcess::systemEnvironment());
+    Environment envLang(Environment::systemEnvironment());
     envLang.setupEnglishOutput();
     proc.setEnvironment(envLang);
     proc.setCommand({debugger.executable, args});