Update clang-tidy configuration and fix some warnings (#1474)

Don't enable coding conventions from unrelated projects. Only enable
generic checks.

.clang-tidy

@@ -1,14 +1,15 @@
-Checks: '*,
-  -altera-unroll-loops,
-  -llvmlibc-callee-namespace,
-  -llvmlibc-implementation-in-namespace,
-  -llvmlibc-restrict-system-libc-headers,
-  -llvm-header-guard,
-  -llvm-namespace-comment,
-  -google-build-using-namespace,
-  -google-runtime-int,
-  -google-readability-namespace-comments,
-  -fuchsia-statically-constructed-objects,
+Checks: 'bugprone-*,
+  cert-*,
+  cppcoreguidelines-*,
+  hicpp-*,
+  misc-*,
+  modernize-*,
+  performance-*,
+  portability-*,
+  readability-*,
+  fuchsia-trailing-return,
+  -cert-err58-cpp,
+  -cert-err60-cpp,
   -cppcoreguidelines-prefer-member-initializer,
   -cppcoreguidelines-pro-bounds-array-to-pointer-decay,
   -cppcoreguidelines-pro-bounds-constant-array-index,
@@ -20,10 +21,6 @@ Checks: '*,
   -cppcoreguidelines-avoid-non-const-global-variables,
   -cppcoreguidelines-avoid-c-arrays,
   -cppcoreguidelines-special-member-functions,
-  -readability-magic-numbers,
-  -readability-uppercase-literal-suffix,
-  -modernize-use-trailing-return-type,
-  -modernize-avoid-c-arrays,
   -hicpp-avoid-c-arrays,
   -hicpp-uppercase-literal-suffix,
   -hicpp-vararg,
@@ -31,8 +28,10 @@ Checks: '*,
   -hicpp-no-array-decay,
   -hicpp-signed-bitwise,
   -hicpp-special-member-functions,
-  -cert-err58-cpp,
-  -cert-err60-cpp'
+  -modernize-use-trailing-return-type,
+  -modernize-avoid-c-arrays,
+  -readability-magic-numbers,
+  -readability-uppercase-literal-suffix'
 CheckOptions:
   - key: readability-function-cognitive-complexity.Threshold
     value: 100