Bug 1154803 - Put our sigaction diversion in __sigaction if it exists. r=glandium, a=sledru

mozglue/linker/ElfLoader.cpp

@@ -1112,8 +1112,17 @@ SEGVHandler::FinishInitialization()
    */
   void *libc = dlopen("libc.so", RTLD_GLOBAL | RTLD_LAZY);
   if (libc) {
-    libc_sigaction =
+    /*
-      reinterpret_cast<sigaction_func>(dlsym(libc, "sigaction"));
+     * Lollipop bionic only has a small trampoline in sigaction, with the real
+     * work happening in __sigaction. Divert there instead of sigaction if it exists.
+     * Bug 1154803
+     */
+    libc_sigaction = reinterpret_cast<sigaction_func>(dlsym(libc, "__sigaction"));
+
+    if (!libc_sigaction) {
+      libc_sigaction =
+        reinterpret_cast<sigaction_func>(dlsym(libc, "sigaction"));
+    }
   } else
 #endif
   {