[basic.fundamental] Use "std::" prefix consistently for library type aliases

Author: eisenwave

source/basic.tex

@@ -5482,7 +5482,7 @@
 \indextext{type!underlying!\idxcode{char16_t}}%
 \indextext{type!underlying!\idxcode{char32_t}}%
 Types \keyword{char16_t} and \keyword{char32_t} denote distinct types
-whose underlying types are \tcode{uint_least16_t} and \tcode{uint_least32_t},
+whose underlying types are \tcode{std::uint_least16_t} and \tcode{std::uint_least32_t},
 respectively, in \libheaderref{cstdint}.
 
 \pnum