Simplify `#if defined(foo)` to `#ifdef`

verible/common/util/init-command-line.cc

diff --git a/verible/common/util/init-command-line.cc b/verible/common/util/init-command-line.cc
index 371ffe4..74ef42c 100644
--- a/verible/common/util/init-command-line.cc
+++ b/verible/common/util/init-command-line.cc
@@ -104,7 +104,7 @@
 
   // Print stacktrace on issue, but not if --config=asan
   // which comes with its own stacktrace handling.
-#if !defined(__SANITIZE_ADDRESS__)
+#ifndef __SANITIZE_ADDRESS__
   absl::FailureSignalHandlerOptions options;
   absl::InstallFailureSignalHandler(options);
 #endif

verible/verilog/analysis/lint-rule-registry_test.cc

diff --git a/verible/verilog/analysis/lint-rule-registry_test.cc b/verible/verilog/analysis/lint-rule-registry_test.cc
index 75fc130..6fbb147 100644
--- a/verible/verilog/analysis/lint-rule-registry_test.cc
+++ b/verible/verilog/analysis/lint-rule-registry_test.cc
@@ -102,7 +102,7 @@
 TEST(LintRuleRegistryTest, CreateTreeLintRuleValid) {
   auto any_rule = CreateSyntaxTreeLintRule("test-rule-1");
   EXPECT_NE(any_rule, nullptr);
-#if defined(__GXX_RTTI)
+#ifdef __GXX_RTTI
   auto rule_1 = dynamic_cast<TreeRule1 *>(any_rule.get());
   EXPECT_NE(rule_1, nullptr);
 #endif
@@ -155,7 +155,7 @@
 TEST(LintRuleRegistryTest, CreateTokenLintRuleValid) {
   auto any_rule = CreateTokenStreamLintRule("token-rule-1");
   EXPECT_NE(any_rule, nullptr);
-#if defined(__GXX_RTTI)
+#ifdef __GXX_RTTI
   auto rule_1 = dynamic_cast<TokenRule1 *>(any_rule.get());
   EXPECT_NE(rule_1, nullptr);
 #endif
@@ -204,7 +204,7 @@
 TEST(LintRuleRegistryTest, CreateLineLintRuleValid) {
   auto any_rule = CreateLineLintRule("line-rule-1");
   EXPECT_NE(any_rule, nullptr);
-#if defined(__GXX_RTTI)
+#ifdef __GXX_RTTI
   auto rule_1 = dynamic_cast<LineRule1 *>(any_rule.get());
   EXPECT_NE(rule_1, nullptr);
 #endif
@@ -253,7 +253,7 @@
 TEST(LintRuleRegistryTest, CreateTextLintRuleValid) {
   auto any_rule = CreateTextStructureLintRule("text-rule-1");
   EXPECT_NE(any_rule, nullptr);
-#if defined(__GXX_RTTI)
+#ifdef __GXX_RTTI
   auto rule_1 = dynamic_cast<TextRule1 *>(any_rule.get());
   EXPECT_NE(rule_1, nullptr);
 #endif