clang: Enable -Weverything, fix all warnings

This change fixes the following warnings:

```
    -Wc++98-compat-extra-semi
    -Wc++98-compat-local-type-template-args
    -Wc++98-compat-pedantic
    -Wc++98-compat
    -Wcomma
    -Wdeprecated-copy-dtor
    -Wexit-time-destructors
    -Wextra-semi-stmt
    -Wextra-semi
    -Wfloat-conversion
    -Wfloat-equal
    -Wformat-nonliteral
    -Wglobal-constructors
    -Winconsistent-missing-destructor-override
    -Wnon-virtual-dtor
    -Wold-style-cast
    -Wpadded
    -Wreturn-std-move-in-c++11
    -Wshadow-field-in-constructor
    -Wshadow-uncaptured-local
    -Wshift-sign-overflow
    -Wsign-conversion
    -Wundef
    -Wunreachable-code-return
    -Wused-but-marked-unused
    -Wweak-vtables
    -Wzero-as-null-pointer-constant
```

include/dap/typeof.h

@@ -26,7 +26,7 @@ namespace dap {
 // template type T.
 template <typename T>
 struct BasicTypeInfo : public TypeInfo {
-  BasicTypeInfo(const std::string& name) : name_(name) {}
+  constexpr BasicTypeInfo(std::string&& name) : name_(std::move(name)) {}
 
   // TypeInfo compliance
   inline std::string name() const { return name_; }
@@ -88,6 +88,15 @@ struct TypeOf<null> {
   static const TypeInfo* type();
 };
 
+// TypeOf for template types requires dynamic generation of type information,
+// triggering the clang -Wexit-time-destructors warning.
+// TODO(bclayton): See if there's a way to avoid this, without requiring manual
+// instantiation of each type.
+#ifdef __clang__
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wexit-time-destructors"
+#endif  // __clang__
+
 template <typename T>
 struct TypeOf<array<T>> {
   static inline const TypeInfo* type() {
@@ -114,6 +123,10 @@ struct TypeOf<optional<T>> {
   }
 };
 
+#ifdef __clang__
+#pragma clang diagnostic pop
+#endif  // __clang__
+
 // DAP_OFFSETOF() macro is a generalization of the offsetof() macro defined in
 // <cstddef>. It evaluates to the offset of the given field, with fewer
 // restrictions than offsetof(). We cast the address '32' and subtract it again,