Set LD_LIBRARY_PATH in unix run environments.

Similarly to how PATH is set up for Windows. The background is that
without it plugin loading can pull in incompatible Qt libraries if the
binary is compiled with RUNPATH instead of RPATH.

Reviewed-by: Daniel Teske

src/libs/utils/environment.cpp

@@ -174,6 +174,27 @@ void Environment::prependOrSetPath(const QString &value)
     prependOrSet(QLatin1String("PATH"), QDir::toNativeSeparators(value), QString(sep));
 }
 
+void Environment::prependOrSetLibrarySearchPath(const QString &value)
+{
+#ifdef Q_OS_WIN
+    const QChar sep = QLatin1Char(';');
+#else
+    const QChar sep = QLatin1Char(':');
+#endif
+
+#ifdef Q_OS_WIN
+    const QLatin1String path("PATH");
+#elif defined(Q_OS_MAC)
+    const QLatin1String path("DYLD_LIBRARY_PATH");
+#elif defined(Q_OS_UNIX)
+    const QLatin1String path("LD_LIBRARY_PATH");
+#else
+    return;
+#endif
+
+    prependOrSet(path, QDir::toNativeSeparators(value), QString(sep));
+}
+
 Environment Environment::systemEnvironment()
 {
     return Environment(QProcess::systemEnvironment());