Add pybind11 library (#5935)

First, thanks for maintaining compiler explorer. It is a wonderful tool.

I have been playing with EDG/reflections on godbolt.org and decided to
make a proof of concept library for python bindings that relies on
reflections. To make my life easier, I wanted to depend on pybind11,
instead of re-learning CPython API.
That brings me to this pull request. I would appreciate having pybind11
available in godbolt.

I am not sure if I am missing anything regarding this. Pybind11 is
header-only and the path specified is the one that should be passed to
`-isystem`.
Also, the issue template mentions tests, but I am not sure how or even
if tests are needed for this change.

I will also understand if you would rather not add more libraries to the
compiler explorer image for the sake of its size.

etc/config/c++.amazon.properties

@@ -2915,7 +2915,7 @@ compiler.edg-6_5-default-13.name=EDG 6.5
 #################################
 #################################
 # Installed libs
-libs=abseil:array:async_simple:belleviews:benchmark:benri:blaze:boost:bmulti:brigand:catch2:cctz:cereal:cmcstl2:cnl:cppcoro:cppitertools:cpptrace:crosscables:ctbignum:cthash:ctre:date:dataframe:dawjson:dlib:doctest:eastl:eigen:enoki:entt:etl:eve:expected_lite:fastor:fmt:gemmlowp:glaze:glm:gnufs:gnulibbacktrace:gnuexp:googletest:gsl:hdf5:hedley:hfsm:highfive:highway:hotels-template-library:immer:jsoncons:jsoncpp:kiwaku:kokkos:kumi:kvasir:kyosu:lager:lagom:lexy:libassert:libbpf:libguarded:libsimdpp:libuv:llvm:llvmfs:lua:magic_enum:mfem:mlir:mp-coro:mp-units:namedtype:nanorange:nlohmann_json:nsimd:ofw:openssl:outcome:pegtl:pipes:pugixml:python:rangesv3:raberu:reactive_plus_plus:scnlib:seastar:seqan3:simde:simdjson:sol2:spdlog:spy:stdexec:strong_type:taojson:taskflow:tbb:thinkcell:tlexpected:toml11:tomlplusplus:trompeloeil:tts:type_safe:unifex:ureact:vcl:xercesc:xsimd:xtensor:xtl:yomm2:zug:cli11:avr-libstdcpp:curl:copperspice:sqlite:ztdcuneicode:ztdencodingtables:ztdidk:ztdstaticcontainers:ztdtext:ztdplatform:qt:pcre2
+libs=abseil:array:async_simple:belleviews:benchmark:benri:blaze:boost:bmulti:brigand:catch2:cctz:cereal:cmcstl2:cnl:cppcoro:cppitertools:cpptrace:crosscables:ctbignum:cthash:ctre:date:dataframe:dawjson:dlib:doctest:eastl:eigen:enoki:entt:etl:eve:expected_lite:fastor:fmt:gemmlowp:glaze:glm:gnufs:gnulibbacktrace:gnuexp:googletest:gsl:hdf5:hedley:hfsm:highfive:highway:hotels-template-library:immer:jsoncons:jsoncpp:kiwaku:kokkos:kumi:kvasir:kyosu:lager:lagom:lexy:libassert:libbpf:libguarded:libsimdpp:libuv:llvm:llvmfs:lua:magic_enum:mfem:mlir:mp-coro:mp-units:namedtype:nanorange:nlohmann_json:nsimd:ofw:openssl:outcome:pegtl:pipes:pugixml:pybind11:python:rangesv3:raberu:reactive_plus_plus:scnlib:seastar:seqan3:simde:simdjson:sol2:spdlog:spy:stdexec:strong_type:taojson:taskflow:tbb:thinkcell:tlexpected:toml11:tomlplusplus:trompeloeil:tts:type_safe:unifex:ureact:vcl:xercesc:xsimd:xtensor:xtl:yomm2:zug:cli11:avr-libstdcpp:curl:copperspice:sqlite:ztdcuneicode:ztdencodingtables:ztdidk:ztdstaticcontainers:ztdtext:ztdplatform:qt:pcre2
 
 libs.abseil.name=Abseil
 libs.abseil.versions=trunk
@@ -4043,6 +4043,14 @@ libs.pugixml.staticliblink=pugixml
 libs.pugixml.versions.1114.version=1.11.4
 libs.pugixml.versions.1114.path=/opt/compiler-explorer/libs/pugixml/v1.11.4/src/
 
+libs.pybind11.name=Pybind11
+libs.pybind11.url=https://github.com/pybind/pybind11
+libs.pybind11.versions=trunk:2_11_1
+libs.pybind11.versions.trunk.version=trunk
+libs.pybind11.versions.trunk.path=/opt/compiler-explorer/libs/pybind11/trunk/include
+libs.pybind11.versions.2_11_1.version=v2.11.1
+libs.pybind11.versions.2_11_1.path=/opt/compiler-explorer/libs/pybind11/v2.11.1/include
+
 libs.python.name=Python
 libs.python.url=https://python.org
 libs.python.versions=359:3610:376:381