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

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

src/sticker/StickerDatabase.cxx

@@ -151,7 +151,7 @@ sticker_global_finish()
 }
 
 bool
-sticker_enabled()
+sticker_enabled() noexcept
 {
 	return sticker_db != nullptr;
 }
@@ -328,7 +328,7 @@ sticker_free(Sticker *sticker)
 }
 
 const char *
-sticker_get_value(const Sticker &sticker, const char *name)
+sticker_get_value(const Sticker &sticker, const char *name) noexcept
 {
 	auto i = sticker.table.find(name);
 	if (i == sticker.table.end())

src/sticker/StickerDatabase.hxx

@@ -69,7 +69,7 @@ sticker_global_finish();
  */
 gcc_const
 bool
-sticker_enabled();
+sticker_enabled() noexcept;
 
 /**
  * Returns one value from an object's sticker record.  Returns an
@@ -125,7 +125,7 @@ sticker_free(Sticker *sticker);
  */
 gcc_pure
 const char *
-sticker_get_value(const Sticker &sticker, const char *name);
+sticker_get_value(const Sticker &sticker, const char *name) noexcept;
 
 /**
  * Iterates over all sticker items in a sticker.