Missing pdjson.h in installation

[r-burns]

Hi! I'm updating Nixpkgs's various build2 packages from 0.15.0 to 0.16.0 and noticed this build failure when trying to bump bpkg:

In file included from /build/bpkg-0.16.0/bpkg/system-package-manager.cxx:10:
/nix/store/czjlc837wncb400i61arfv0v9f6wms5z-libbutl-0.16.0-dev/include/libbutl/json/parser.hxx:19:10: fatal error: libbutl/json/pdjson.h: No such file or directory
   19 | #include <libbutl/json/pdjson.h> // Implementation details.
      |          ^~~~~~~~~~~~~~~~~~~~~~~
compilation terminated.
error: process g++ exited with code 1

It looks to me like the pdjson.h header is now needed by bpkg but is not installed by libbutl's buildfiles. I was able to work around it with this small patch to also install libbutl's .h files, although I'm not sure if this is the correct solution:

--- a/libbutl/buildfile
+++ b/libbutl/buildfile
@@ -1,7 +1,7 @@
 # file      : libbutl/buildfile
 # license   : MIT; see accompanying LICENSE file
 
-lib{butl}: {hxx ixx txx cxx}{** -uuid-* +uuid-io         \
+lib{butl}: {h hxx ixx txx cxx}{** -uuid-* +uuid-io       \
                                 -win32-utility           \
                                 -mingw-*                 \
                                 -version                 \
@@ -154,7 +154,7 @@ else
 # Install into the libbutl/ subdirectory of, say, /usr/include/
 # recreating subdirectories.
 #
-{hxx ixx txx}{*}:
+{h hxx ixx txx}{*}:
 {
   install         = include/libbutl/
   install.subdirs = true