*: add "noexcept" to many, many function prototypes

This eliminates some overhead, because the compiler doesn't need to
consider these functions throwing.

src/fs/Path.cxx

@@ -24,7 +24,7 @@
 #include <stdexcept>
 
 std::string
-Path::ToUTF8() const
+Path::ToUTF8() const noexcept
 {
 	try {
 		return ::PathToUTF8(c_str());
@@ -34,7 +34,7 @@ Path::ToUTF8() const
 }
 
 Path::const_pointer_type
-Path::GetSuffix() const
+Path::GetSuffix() const noexcept
 {
 	const auto base = GetBase().c_str();
 	const auto *dot = StringFindLast(base, '.');