string tests failing on 32bit system

==== string-4.12.0 string first, start index FAILED
==== Contents of test case:

    run {string first \u7266 abc\u7266x 4}

---- Result was:
4294967295
---- Result should have been (exact matching):
-1
==== string-4.12.0 FAILED


==== string-4.8.1 string first FAILED
==== Contents of test case:

    run {string first "" x123xx345xxx789xxx012}

---- Result was:
4294967295
---- Result should have been (exact matching):
-1
==== string-4.8.1 FAILED


==== string-4.12.1 string first, start index FAILED
==== Contents of test case:

    run {string first \u7266 abc\u7266x 4}

---- Result was:
4294967295
---- Result should have been (exact matching):
-1
==== string-4.12.1 FAILED


System:
emiliano@cabernet:~/src/tcl/unix$ uname -a
NetBSD cabernet.vinotinto.com.ar 7.1 NetBSD 7.1 (GENERIC.201703111743Z) i386

Tcl:
emiliano@cabernet:~/src/tcl/unix$ make shell
LD_LIBRARY_PATH=`pwd`:  TCLLIBPATH="/home/emiliano/src/tcl/unix/pkgs"  TCL_LIBRARY="/home/emiliano/src/tcl/library" ./tclsh 
% parray tcl_platform
tcl_platform(byteOrder)     = littleEndian
tcl_platform(engine)        = Tcl
tcl_platform(machine)       = i386
tcl_platform(os)            = NetBSD
tcl_platform(osVersion)     = 7.1
tcl_platform(pathSeparator) = :
tcl_platform(platform)      = unix
tcl_platform(pointerSize)   = 4
tcl_platform(threaded)      = 1
tcl_platform(user)          = emiliano
tcl_platform(wordSize)      = 4
% emiliano@cabernet:~/src/tcl/unix$ fossil info
project-name: Tcl Source Code
repository:   /home/emiliano/src/tcl/../tcl.fossil
local-root:   /home/emiliano/src/tcl/
config-db:    /home/emiliano/.fossil
project-code: 1ec9da4c469c29f4717e2a967fe6b916d9c8c06e
checkout:     c92a5c4373df89ffbb61fe4d66285d33f2544ace 2018-12-11 20:02:40 UTC
parent:       555b2825daf6434f47eb9aec9deb5f1656f806e3 2018-12-08 17:36:57 UTC
merged-from:  a6cbc60ca29e236bb2884a7c283dc2bda6dce008 2018-12-11 19:43:11 UTC
merged-into:  47da08c479b942b8e71a96ccdcb959cdffce6b9e 2018-12-11 20:29:10 UTC
tags:         trunk
comment:      Merge 8.7 In test-cases, don't load Tcltest package if it isn't
              actually used. Another round of size_t related improvements.
              Nothing functional. Also improve some comments. (user:
              jan.nijtmans)
check-ins:    24044