Rebuild for LLVM 11.1

[h-vetinari]

Closes #21

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

I do have some suggestions for making it better though...

For recipe:

• License is not an SPDX identifier (or a custom LicenseRef) nor an SPDX license expression.

Documentation on acceptable licenses can be found here.

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[h-vetinari]

I don't understand how this still runs into conda-forge/llvmdev-feedstock#117 despite using the builds from conda-forge/llvmdev-feedstock#118. Should I add a test to llvm-tools that llvm-mt can be called...?

[h-vetinari]

Ah... Just saw that conda-forge/llvmdev-feedstock@abfc126 only arrived with 12.0.0. Will make a new 11.1 build.

[h-vetinari]

See conda-forge/llvmdev-feedstock#144

[h-vetinari]

I'm out of ideas why llvm-mt fails with missing libxml2. I added a test in conda-forge/llvmdev-feedstock#144, yet calling it here fails again:

    cmd.exe /C "cd . && D:\bld\flang-split_1644789667146\_build_env\Library\bin\cmake.exe -E vs_link_exe --intdir=CMakeFiles\cmTC_57d15.dir --rc=C:\PROGRA~2\WI3CF2~1\10\bin\100220~1.0\x64\rc.exe --mt=D:\bld\flang-split_1644789667146\_h_env\Library\bin\llvm-mt.exe --manifests  -- C:\PROGRA~1\LLVM\bin\lld-link.exe /nologo CMakeFiles\cmTC_57d15.dir\testCCompiler.c.obj  /out:cmTC_57d15.exe /implib:cmTC_57d15.lib /pdb:cmTC_57d15.pdb /version:0.0 /machine:x64  /debug /INCREMENTAL /subsystem:console  kernel32.lib user32.lib gdi32.lib winspool.lib shell32.lib ole32.lib oleaut32.lib uuid.lib comdlg32.lib advapi32.lib && cd ."
    MT: command "D:\bld\flang-split_1644789667146\_h_env\Library\bin\llvm-mt.exe /nologo /manifest CMakeFiles\cmTC_57d15.dir/intermediate.manifest /out:CMakeFiles\cmTC_57d15.dir/embed.manifest /notify_update" failed (exit code 0x1) with the following output:
    llvm-mt: error: no libxml2
    llvm-mt: ignoring unsupported 'notify_update' option

This is the environment (i.e. correct llvm-tools build):

## Package Plan ##

  environment location: D:\bld\flang-split_1644789667146\_h_env


The following NEW packages will be INSTALLED:

    clang:          11.1.0-h57928b3_1         conda-forge
    clang-11:       11.1.0-default_h5c34c98_1 conda-forge
    clang-tools:    11.1.0-default_h5c34c98_1 conda-forge
    clangdev:       11.1.0-default_h5c34c98_1 conda-forge
    clangxx:        11.1.0-default_h5c34c98_1 conda-forge
    libclang:       11.1.0-default_h5c34c98_1 conda-forge
    libclang-cpp:   11.1.0-default_h5c34c98_1 conda-forge
    libiconv:       1.16-he774522_0           conda-forge
    libllvm11:      11.1.0-hab3b255_3         conda-forge
    libxml2:        2.9.12-hf5bbc77_1         conda-forge
    libzlib:        1.2.11-h8ffe710_1013      conda-forge
    llvm-openmp:    11.1.0-h2d74725_1         conda-forge
    llvm-tools:     11.1.0-ha327e53_3         conda-forge
    llvmdev:        11.1.0-hab3b255_3         conda-forge
    ucrt:           10.0.20348.0-h57928b3_0   conda-forge
    vc:             14.2-hb210afc_6           conda-forge
    vs2015_runtime: 14.29.30037-h902a5da_6    conda-forge
    zlib:           1.2.11-h8ffe710_1013      conda-forge

[h-vetinari]

'fraid I'm gonna need help for this one. (last two commits were a foolish hope that didn't pan out; rebased out again, was just adding llvm-tools resp. libxml2 as explicit host deps)

[h-vetinari]

@isuruf, any ideas what might be causing the missing libxml2 for llvm-tools? It's enabled in the build script, specified as a host dep, and tested successfully (well, with a -help call...) in the llvmdev-feedstock, but ends up failing here.

[h-vetinari]

I'd like to unblock the newer openblas builds, and getting this PR unstuck would help a lot, but I cannot figure out why libxml2 would not be found....

[h-vetinari]

Obsolete