Change channel to "Second Life Alpha" so installers don't wipe 1.23

indra/llcommon/llversionviewer.h

@@ -36,7 +36,7 @@
 const S32 LL_VERSION_MAJOR = 2;
 const S32 LL_VERSION_MINOR = 0;
 const S32 LL_VERSION_PATCH = 0;
-const S32 LL_VERSION_BUILD = 200030;
+const S32 LL_VERSION_BUILD = 999999;
 
 const char * const LL_CHANNEL = "Second Life Developer";