Utils: Introduce new class OsSpecificAspects.

This is basically a generalization of HostOsInfo for
a system that might not be the host system. HostOsInfo
is now implemented in terms of the new class.
Prospective use case: Untie Utils::Environment from
the host system.

Change-Id: If333b96674652109fcb0ad79f75aaaf5e86e17e3
Reviewed-by: hjk <hjk121@nokiamail.com>
Reviewed-by: Daniel Teske <daniel.teske@digia.com>

src/plugins/android/androidconfigurations.cpp

@@ -335,13 +335,13 @@ void AndroidConfigurations::detectToolchainHost()
 {
     QStringList hostPatterns;
     switch (HostOsInfo::hostOs()) {
-    case HostOsInfo::HostOsLinux:
+    case OsTypeLinux:
         hostPatterns << QLatin1String("linux*");
         break;
-    case HostOsInfo::HostOsWindows:
+    case OsTypeWindows:
         hostPatterns << QLatin1String("windows*");
         break;
-    case HostOsInfo::HostOsMac:
+    case OsTypeMac:
         hostPatterns << QLatin1String("darwin*");
         break;
     default: /* unknown host */ return;