devel/pango build failure using clang

[Frédéric Fauberteau <triaxx%NetBSD.org@localhost>]

I do not really understand why hb.h is not found since '-I/home/triaxx/pkg/include/harfbuzz' is provided to g-ir-scanner. I tried to build devel/pango from an unprivileged bootstrap. The most surprising thing is that I successfully built devel/pango from un privileged bootstrap for the very same version and on the very same system.

I'm interested in any idea to track the g-ir-scanner error down.

[34/132] Generating Pango-1.0.gir with a custom command                                                                                                                                                                                                                          
FAILED: pango/Pango-1.0.gir                                                                                                                                                                                                                                                      
/home/triaxx/pkg/bin/g-ir-scanner -I/home/triaxx/pkg/include/gobject-introspection-1.0 -I/home/triaxx/pkg/include -I/home/triaxx/pkg/include/glib-2.0 -I/home/triaxx/pkg/lib/glib-2.0/include -pthread --no-libtool --namespace=Pango --nsversion=1.0 --warn-all --output pango/P
ango-1.0.gir --c-include=pango/pango.h --quiet -I/usr/home/triaxx/.pkgsrc/work/devel/pango/work/pango-1.44.7/pango -I/usr/home/triaxx/.pkgsrc/work/devel/pango/work/pango-1.44.7/output/pango -I./. -I../. -I./pango/. -I../pango/. --filelist=/usr/home/triaxx/.pkgsrc/work/deve
l/pango/work/pango-1.44.7/output/pango/82b5c0c@@pango-1.0@sha/Pango_1.0_gir_filelist --include=GObject-2.0 --include=cairo-1.0 --symbol-prefix=pango --identifier-prefix=Pango --pkg-export=pango --cflags-begin -D_POSIX_C_SOURCE=200809L -D_POSIX_THREAD_SAFE_FUNCTIONS -D_GNU_
SOURCE -I./. -I../. -I./pango/. -I../pango/. -I/home/triaxx/pkg/include/glib-2.0 -I/home/triaxx/pkg/lib/glib-2.0/include -I/home/triaxx/pkg/include -I/home/triaxx/pkg/include/fribidi -I/home/triaxx/pkg/include/harfbuzz -I/home/triaxx/pkg/include/freetype2 -I/home/triaxx/pk
g/include/uuid -D_THREAD_SAFE -D_REENTRANT -I/home/triaxx/pkg/include/cairo -I/home/triaxx/pkg/include/pixman-1 -I/home/triaxx/pkg/include/libpng16 -I/home/triaxx/pkg/include -I/usr/include -I/home/triaxx/pkg/include/freetype2 -I/home/triaxx/pkg/include/glib-2.0 -I/home/tr
iaxx/pkg/include/gio-unix-2.0 -I/home/triaxx/pkg/lib/glib-2.0/include -I/home/triaxx/pkg/include/python3.8 -I/home/triaxx/pkg/include -I/usr/include -I/home/triaxx/pkg/include/freetype2 -I/home/triaxx/pkg/include/glib-2.0 -I/home/triaxx/pkg/include/gio-unix-2.0 -I/home/tri
axx/pkg/lib/glib-2.0/include -I/home/triaxx/pkg/include/python3.8 --cflags-end --library pango-1.0 -L/usr/home/triaxx/.pkgsrc/work/devel/pango/work/pango-1.44.7/output/pango -L/home/triaxx/pkg/lib -L/usr/lib --extra-library=m -L/home/triaxx/pkg/lib --extra-library=glib-2.0
 --extra-library=intl --extra-library=gobject-2.0 --extra-library=fribidi --extra-library=harfbuzz --extra-library=fontconfig --extra-library=freetype --extra-library=Xrender --extra-library=X11 --extra-library=Xft --extra-library=cairo --sources-top-dirs /usr/home/triaxx/
.pkgsrc/work/devel/pango/work/pango-1.44.7/subprojects/ --sources-top-dirs /usr/home/triaxx/.pkgsrc/work/devel/pango/work/pango-1.44.7/output/subprojects/
In file included from /usr/home/triaxx/.pkgsrc/work/devel/pango/work/pango-1.44.7/output/g-ir-cpp-pismx0oi.c:4:
In file included from /usr/home/triaxx/.pkgsrc/work/devel/pango/work/pango-1.44.7/pango/pango.h:25:
In file included from /usr/home/triaxx/.pkgsrc/work/devel/pango/work/pango-1.44.7/pango/pango-attributes.h:25:
In file included from /usr/home/triaxx/.pkgsrc/work/devel/pango/work/pango-1.44.7/pango/pango-font.h:25:
/usr/home/triaxx/.pkgsrc/work/devel/pango/work/pango-1.44.7/pango/pango-coverage.h:28:10: fatal error: 'hb.h' file not found
#include <hb.h>
         ^~~~~~
1 error generated.
Traceback (most recent call last):
  File "/home/triaxx/pkg/lib/python3.8/distutils/unixccompiler.py", line 107, in preprocess
    self.spawn(pp_args)
  File "/home/triaxx/pkg/lib/python3.8/distutils/ccompiler.py", line 910, in spawn
    spawn(cmd, dry_run=self.dry_run)
  File "/home/triaxx/pkg/lib/python3.8/distutils/spawn.py", line 36, in spawn
    _spawn_posix(cmd, search_path, dry_run=dry_run)
  File "/home/triaxx/pkg/lib/python3.8/distutils/spawn.py", line 157, in _spawn_posix
    raise DistutilsExecError(
distutils.errors.DistutilsExecError: command 'clang' failed with exit status 1