Add POSIX 2024 NSIG_MAX.

https://www.austingroupbugs.net/view.php?id=741

Change-Id: I89117528e1ed8ab0f922bfa394fab16003070eab
diff --git a/tests/headers/posix/limits_h.c b/tests/headers/posix/limits_h.c
index 0ca80a5..0a3bc1c 100644
--- a/tests/headers/posix/limits_h.c
+++ b/tests/headers/posix/limits_h.c
@@ -58,6 +58,9 @@
 #if !defined(__BIONIC__)
   MACRO(MQ_PRIO_MAX);
 #endif
+#if defined(__BIONIC__)
+  MACRO(NSIG_MAX);
+#endif
 #if !defined(__BIONIC__) && !defined(__GLIBC__) && !defined(ANDROID_HOST_MUSL)
   MACRO(OPEN_MAX);
 #endif
diff --git a/tests/limits_test.cpp b/tests/limits_test.cpp
index bc13a3f..64d9a33 100644
--- a/tests/limits_test.cpp
+++ b/tests/limits_test.cpp
@@ -78,3 +78,11 @@
 #error ULLONG_MAX
 #endif
 }
+
+TEST(limits, highest_signal_plus_one) {
+#if defined(__BIONIC__)
+  ASSERT_EQ(65, NSIG_MAX);
+#endif
+  ASSERT_EQ(65, NSIG);
+  ASSERT_EQ(65, _NSIG);
+}