Modernize codebase by replacing NULL with nullptr

Fixes -Wzero-as-null-pointer-constant warning.

Test: m
Bug: 68236239
Change-Id: I226a0599db4f7c3557e55cade7869d00bd314949
diff --git a/server/NetdConstants.cpp b/server/NetdConstants.cpp
index 2f0500f..0754275 100644
--- a/server/NetdConstants.cpp
+++ b/server/NetdConstants.cpp
@@ -111,7 +111,7 @@
     addrinfo hints = {
         .ai_flags = AI_NUMERICHOST,
     };
-    int ret = getaddrinfo(addressString.c_str(), NULL, &hints, &res);
+    int ret = getaddrinfo(addressString.c_str(), nullptr, &hints, &res);
     if (ret || !res) {
         return -EINVAL;  // getaddrinfo return values are not errno values.
     }
@@ -161,7 +161,7 @@
 
     sigemptyset(&mask);
     sigaddset(&mask, SIGPIPE);
-    if (sigprocmask(SIG_BLOCK, &mask, NULL) != 0)
+    if (sigprocmask(SIG_BLOCK, &mask, nullptr) != 0)
         ALOGW("WARNING: SIGPIPE not blocked\n");
 }