sync trunk with TeXLive to revision 46500.

source/build-aux/config.guess

source/libs/README

source/m4/kpse-pkgs.m4

source/texk/README

source/texk/kpathsea/ChangeLog

source/texk/kpathsea/kpsewhich.c

source/texk/kpathsea/pathsearch.c

source/texk/kpathsea/readable.c

source/texk/kpathsea/readable.h

source/texk/kpathsea/str-list.c

source/texk/kpathsea/str-list.h

source/texk/kpathsea/tex-file.c

source/texk/web2c/ChangeLog

source/texk/web2c/Makefile.am

source/texk/web2c/Makefile.in

source/texk/web2c/configure

source/texk/web2c/configure.ac

source/texk/web2c/cwebboot.cin

source/texk/web2c/cwebdir/ChangeLog

source/texk/web2c/cwebdir/common.c