Log Message:
meta-pkgs/boost: Work around find -exec portability issue.

Solaris find(1) only replaces arguments that are exactly `{}' -- it
doesn't replace `{}' within arguments with other content -- so the
way this is done now leads to weird-looking failures like:

ERROR: The following files are in \ 
/home/pbulk/build/devel/boost-libs/work/.destdir/opt/pkg but not in the PLIST:
ERROR:         \ 
/home/pbulk/build/devel/boost-libs/work/.destdir/opt/pkg/lib/cmake/Boost-1.87.0/ \ 
{}
ERROR:         \ 
/home/pbulk/build/devel/boost-libs/work/.destdir/opt/pkg/lib/cmake/boost_atomic- \ 
1.87.0/{}

No revbump because this only fixes the build in environments where
boost previously failed to build altogether because of PLIST
mismatches; no change to builds that worked.

However, it looks like this is missing a lot of files, and it's not
fatal because we didn't use ${RUN} (and didn't use `set -e'
explicitly either) so nobody noticed before:

install: \ 
/home/riastradh/pkgsrc/current/work/devel/boost-libs/work/.destdir/home/riastradh/pkgsrc/current/pkg/lib/cmake/./boost_stacktrace_from_exception-1.87.0/boost_stacktrace_from_exception-config-version.cmake: \ 
open: No such file or directory
install: \ 
/home/riastradh/pkgsrc/current/work/devel/boost-libs/work/.destdir/home/riastradh/pkgsrc/current/pkg/lib/cmake/./boost_stacktrace_from_exception-1.87.0/libboost_stacktrace_from_exception-variant-shared.cmake: \ 
open: No such file or directory
...