Fix modernize-use-nullptr clang-tidy issues

This CL also includes a few exceptions to the android-cloexec-open
check in profile_assistant_test.cc, which are required to make
clang-tidy run without any errors.

Bug: 213953102
Test: m tidy-art
Change-Id: I4d99b51a2d2c1837ef350d44965d386738b74065
diff --git a/build/Android.bp b/build/Android.bp
index 434a658..c0323b4 100644
--- a/build/Android.bp
+++ b/build/Android.bp
@@ -36,6 +36,7 @@
     "bugprone-virtual-near-miss",
     "misc-unused-using-decls",
     "modernize-use-bool-literals",
+    "modernize-use-nullptr",
     "performance-faster-string-find",
     "performance-for-range-copy",
     "performance-implicit-conversion-in-loop",
@@ -49,7 +50,6 @@
     // when all files are free of these warnings.
     "android-cloexec-dup",
     "bugprone-unused-return-value",
-    "modernize-use-nullptr",
     "modernize-use-using", // TODO: move to art_clang_tidy_errors after b/236243696 is done
 ]
 
diff --git a/profman/profile_assistant_test.cc b/profman/profile_assistant_test.cc
index 01b385a..4fc8143 100644
--- a/profman/profile_assistant_test.cc
+++ b/profman/profile_assistant_test.cc
@@ -1840,6 +1840,7 @@
 
   // Run profman and pass the dex file with --apk-fd.
   android::base::unique_fd apk_fd(
+      // NOLINTNEXTLINE - Profman needs file to be opened after fork() and exec()
       open(GetTestDexFileName("ProfileTestMultiDex").c_str(), O_RDONLY));
   ASSERT_GE(apk_fd.get(), 0);
 
@@ -1882,6 +1883,7 @@
 
   // Run profman and pass the dex file with --apk-fd.
   android::base::unique_fd apk_fd(
+      // NOLINTNEXTLINE - Profman needs file to be opened after fork() and exec()
       open(GetTestDexFileName("ProfileTestMultiDex").c_str(), O_RDONLY));
   ASSERT_GE(apk_fd.get(), 0);
 
@@ -1919,6 +1921,7 @@
 
   // Run profman and pass the dex file with --apk-fd.
   android::base::unique_fd apk_fd(
+      // NOLINTNEXTLINE - Profman needs file to be opened after fork() and exec()
       open(GetTestDexFileName("ProfileTestMultiDex").c_str(), O_RDONLY));
   ASSERT_GE(apk_fd.get(), 0);
 
@@ -1957,6 +1960,7 @@
 
   // Run profman and pass the real dex file with --apk-fd.
   android::base::unique_fd apk_fd(
+      // NOLINTNEXTLINE - Profman needs file to be opened after fork() and exec()
       open(GetTestDexFileName("ProfileTestMultiDex").c_str(), O_RDONLY));
   ASSERT_GE(apk_fd.get(), 0);
 
@@ -2003,7 +2007,8 @@
 
   // Run profman and pass the dex file with --apk-fd.
   android::base::unique_fd apk_fd(
-      open(GetTestDexFileName("ProfileTestMultiDex").c_str(), O_RDONLY));  // NOLINT
+      // NOLINTNEXTLINE - Profman needs file to be opened after fork() and exec()
+      open(GetTestDexFileName("ProfileTestMultiDex").c_str(), O_RDONLY));
   ASSERT_GE(apk_fd.get(), 0);
 
   std::string profman_cmd = GetProfmanCmd();
@@ -2050,6 +2055,7 @@
 
   // Run profman and pass the real dex file with --apk-fd. It won't match any entry in the profile.
   android::base::unique_fd apk_fd(
+      // NOLINTNEXTLINE - Profman needs file to be opened after fork() and exec()
       open(GetTestDexFileName("ProfileTestMultiDex").c_str(), O_RDONLY));
   ASSERT_GE(apk_fd.get(), 0);
 
@@ -2171,7 +2177,8 @@
 
   // Run profman and pass the dex file with --apk-fd.
   android::base::unique_fd apk_fd(
-      open(GetTestDexFileName("ProfileTestMultiDex").c_str(), O_RDONLY));  // NOLINT
+      // NOLINTNEXTLINE - Profman needs file to be opened after fork() and exec()
+      open(GetTestDexFileName("ProfileTestMultiDex").c_str(), O_RDONLY));
   ASSERT_GE(apk_fd.get(), 0);
 
   std::string profman_cmd = GetProfmanCmd();
diff --git a/runtime/thread.cc b/runtime/thread.cc
index 94c539f..0c146d5 100644
--- a/runtime/thread.cc
+++ b/runtime/thread.cc
@@ -4000,7 +4000,7 @@
         // (PC shall be known thanks to the runtime frame for throwing SIOOBE).
         // Note that JIT does not emit that intrinic implementation.
         const void* pc = reinterpret_cast<const void*>(GetCurrentQuickFramePc());
-        if (pc != 0u && Runtime::Current()->GetHeap()->IsInBootImageOatFile(pc)) {
+        if (pc != nullptr && Runtime::Current()->GetHeap()->IsInBootImageOatFile(pc)) {
           return;
         }
       }