Update maintainer list.

libs/maintainers.txt

@@ -138,6 +138,7 @@ uuid                  Andy Tompkins <atompkins -at- fastmail.fm>
 variant               Eric Friedman <ericbrandon -at- gmail.com>
 vmd                   Edward Diener <eld -at- tropicsoft.com>
 wave                  Hartmut Kaiser <hartmut.kaiser -at- gmail.com>
+winapi                Andrey Semashev <andrey.semashev -at- gmail.com>
 xpressive             Eric Niebler <eric -at- boostpro.com>