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

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

src/lib/curl/Request.cxx

@@ -170,7 +170,7 @@ CurlRequest::Done(CURLcode result)
 
 gcc_pure
 static bool
-IsResponseBoundaryHeader(StringView s)
+IsResponseBoundaryHeader(StringView s) noexcept
 {
 	return s.size > 5 && (memcmp(s.data, "HTTP/", 5) == 0 ||
 			      /* the proprietary "ICY 200 OK" is

src/lib/curl/Version.cxx

@@ -32,7 +32,7 @@
 #include <curl/curl.h>
 
 bool
-IsCurlOlderThan(unsigned version_num)
+IsCurlOlderThan(unsigned version_num) noexcept
 {
 	const auto *const info = curl_version_info(CURLVERSION_FIRST);
 	return info == nullptr || info->version_num < version_num;

src/lib/curl/Version.hxx

@@ -34,6 +34,6 @@
 
 gcc_const
 bool
-IsCurlOlderThan(unsigned version_num);
+IsCurlOlderThan(unsigned version_num) noexcept;
 
 #endif