The uname() function on Solaris can return a non-negative value.
Solaris specific patch, will not send upstream

diff --git a/toolkit/components/startup/nsUserInfoUnix.cpp b/toolkit/components/startup/nsUserInfoUnix.cpp
--- a/toolkit/components/startup/nsUserInfoUnix.cpp
+++ b/toolkit/components/startup/nsUserInfoUnix.cpp
@@ -106,7 +106,7 @@
     char *domainname = nullptr;
 
     // is this portable?  that is a POSIX compliant call, but I need to check
-    if (uname(&buf)) { 
+    if (uname(&buf) < 0) { 
         return rv;
     }