Despite our attempt (build-docs.sh)
to build the documentation with SVG,
it still uses PNG https://llvm.org/doxygen/classllvm_1_1StringRef.html,
and that renders terribly on any high dpi display.
SVG leads to smasller installation and works fine
on all browser (that has been true for _a while_
https://caniuse.com/svg), so this patch just unconditionally build all
dot graphs as SVG in all subprojects and remove the option.
Update the folder titles for targets in the monorepository that have not
seen taken care of for some time. These are the folders that targets are
organized in Visual Studio and XCode (`set_property(TARGET <target>
PROPERTY FOLDER "<title>")`) when using the respective CMake's IDE
generator.
* Ensure that every target is in a folder
* Use a folder hierarchy with each LLVM subproject as a top-level folder
* Use consistent folder names between subprojects
* When using target-creating functions from AddLLVM.cmake, automatically
deduce the folder. This reduces the number of
`set_property`/`set_target_property`, but are still necessary when
`add_custom_target`, `add_executable`, `add_library`, etc. are used. A
LLVM_SUBPROJECT_TITLE definition is used for that in each subproject's
root CMakeLists.txt.
Add stub Sphinx documentation, with configuration copy-pasted from lld and
index page converted from bolt/README.md.
Reviewed By: #bolt, rafauler
Differential Revision: https://reviews.llvm.org/D140156
