"Unknown Type Name" build failure(s) — clang 6.0

Some type detections are failing or wrong assumptions were made. For example, with strace, old configure are doing some tests on the bool (stdbool.h) declaration but fails on:
conftest.c:84:16: error: initializer element is not a compile-time constant
         int xlcbug = 1 / (&(digs + 5)[-2 + (bool) 1] == &digs[4] ? 1 : -1);
                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Provided by the macro AC_HEADER_STDBOOL but removed in recent release of autoconf
PackageVersionSupposed error messageFull log Bug report
collectd 5.8.0-4./src/daemon/configfile.h:92:62: error: unknown type name '_Bool' Log 758481
dmtcp 2.3.1-6./pidwrappers.h:191:20: error: unknown type name '__WAIT_STATUS' Log
freebsd-libs 10.3~svn296373-10./libutil.h:62:9: error: unknown type name '__size_t'; did you mean '__ssize_t'? Log
netexpect 0.22-2proto.h:125:15: error: unknown type name 'WS_NORETURN' Log
otb 6.4.0+dfsg-2ossimRefPtr.h:103:76: error: unknown type name 'nullptr_t'; did you mean 'std::nullptr_t'? Log
spass 3.7-4./SPASS/list.h:57:3: error: unknown type name 'POINTER' Log
syrthes 4.3.0-dfsg1-2syr_cfd_coupling.c:170:8: error: unknown type name 'ple_coupling_mpi_set_t' Log
xcrysden 1.5.60-1xcAppInit.c:511:5: error: unknown type name 'Togl_CmdProc'; did you mean 'Tcl_CmdProc'? Log

8 errors