/usr/include/pangomm-1.4/pangomm/private/ is in libpangomm-1.4-dev 2.38.1-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/pangomm-1.4/pangomm/private/attributes_p.h
/usr/include/pangomm-1.4/pangomm/private/attriter_p.h
/usr/include/pangomm-1.4/pangomm/private/attrlist_p.h
/usr/include/pangomm-1.4/pangomm/private/cairofontmap_p.h
/usr/include/pangomm-1.4/pangomm/private/color_p.h
/usr/include/pangomm-1.4/pangomm/private/context_p.h
/usr/include/pangomm-1.4/pangomm/private/coverage_p.h
/usr/include/pangomm-1.4/pangomm/private/font_p.h
/usr/include/pangomm-1.4/pangomm/private/fontdescription_p.h
/usr/include/pangomm-1.4/pangomm/private/fontface_p.h
/usr/include/pangomm-1.4/pangomm/private/fontfamily_p.h
/usr/include/pangomm-1.4/pangomm/private/fontmap_p.h
/usr/include/pangomm-1.4/pangomm/private/fontmetrics_p.h
/usr/include/pangomm-1.4/pangomm/private/fontset_p.h
/usr/include/pangomm-1.4/pangomm/private/glyph_p.h
/usr/include/pangomm-1.4/pangomm/private/glyphstring_p.h
/usr/include/pangomm-1.4/pangomm/private/item_p.h
/usr/include/pangomm-1.4/pangomm/private/language_p.h
/usr/include/pangomm-1.4/pangomm/private/layout_p.h
/usr/include/pangomm-1.4/pangomm/private/layoutiter_p.h
/usr/include/pangomm-1.4/pangomm/private/layoutline_p.h
/usr/include/pangomm-1.4/pangomm/private/layoutrun_p.h
/usr/include/pangomm-1.4/pangomm/private/rectangle_p.h
/usr/include/pangomm-1.4/pangomm/private/renderer_p.h
/usr/include/pangomm-1.4/pangomm/private/tabarray_p.h