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/Process.cpp b/server/Process.cpp
index f5f1a3d..1890620 100644
--- a/server/Process.cpp
+++ b/server/Process.cpp
@@ -83,7 +83,7 @@
 
     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");
     }
 }