Sync with TeX Live revision 49770 (trunk).

source/build-aux/config.guess

source/build-aux/config.sub

source/build-aux/texinfo.tex

source/libs/README

source/libs/luajit/configure

source/libs/luajit/configure.ac

source/m4/ChangeLog

source/m4/kpse-luajit-flags.m4

source/m4/kpse-pkgs.m4

source/texk/kpathsea/ChangeLog

source/texk/kpathsea/doc/kpathsea.info

source/texk/kpathsea/doc/kpathsea.texi

source/texk/kpathsea/texmf.cnf

source/texk/kpathsea/variable.h

source/texk/web2c/ChangeLog

source/texk/web2c/Makefile.in

source/texk/web2c/NEWS

source/texk/web2c/am/bootstrap.am

source/texk/web2c/am/cweb.am

source/texk/web2c/configure