Filter out reserved signals in functions that take sigset_t.

Prevent processes from blocking libc-reserved signals by filtering them
out.

Bug: http://b/73144101
Test: 32/64-bit bionic-unit-tests-glibc
Test: 32/64-bit bionic-unit-tests on taimen
Change-Id: Ibadcaa7f668ed8be885cc61b67fb4b611fce8b17
diff --git a/libc/bionic/sigaction.cpp b/libc/bionic/sigaction.cpp
index 19a08e6..41923cf 100644
--- a/libc/bionic/sigaction.cpp
+++ b/libc/bionic/sigaction.cpp
@@ -29,6 +29,8 @@
 #include <signal.h>
 #include <string.h>
 
+#include "private/sigrtmin.h"
+
 extern "C" void __restore_rt(void);
 extern "C" void __restore(void);
 
@@ -41,7 +43,7 @@
   if (bionic_new_action != NULL) {
     kernel_new_action.sa_flags = bionic_new_action->sa_flags;
     kernel_new_action.sa_handler = bionic_new_action->sa_handler;
-    kernel_new_action.sa_mask = bionic_new_action->sa_mask;
+    kernel_new_action.sa_mask = filter_reserved_signals(bionic_new_action->sa_mask);
 #if defined(SA_RESTORER)
     kernel_new_action.sa_restorer = bionic_new_action->sa_restorer;
 #if defined(__aarch64__)
@@ -120,6 +122,7 @@
       kernel_new.sa_restorer = (kernel_new.sa_flags & SA_SIGINFO) ? &__restore_rt : &__restore;
     }
 #endif
+    kernel_new.sa_mask = filter_reserved_signals(kernel_new.sa_mask);
   }
 
   return __rt_sigaction(signal,