cmake: Add LLVM_ENABLE_OCAMLDOC to control building OCaml bindings doc

[mgorny]

Summary

Make it possible to control building of OCaml bindings documentation separately via LLVM_ENABLE_OCAMLDOC rather than implicitly enabling it when OCaml bindings are enabled and LLVM_INCLUDE_DOCS is true. This makes it possible to build OCaml bindings and other documentation parts without having additional OCaml documentation dependencies installed.

[whitequark]

LGTM

[mgorny]

Could you commit it, please? I don't have commit access.

[whitequark]

rL279544

CMakeLists.txt

option(LLVM_BUILD_TESTS
   "Build LLVM unit tests. If OFF, just generate build targets." OFF)
 option(LLVM_INCLUDE_TESTS "Generate build targets for the LLVM unit tests." ON)
 option(LLVM_INCLUDE_GO_TESTS "Include the Go bindings tests in test build targets." ON)
 
 option (LLVM_BUILD_DOCS "Build the llvm documentation." OFF)
 option (LLVM_INCLUDE_DOCS "Generate build targets for llvm documentation." ON)
 option (LLVM_ENABLE_DOXYGEN "Use doxygen to generate llvm API documentation." OFF)
 option (LLVM_ENABLE_SPHINX "Use Sphinx to generate llvm documentation." OFF)
+option (LLVM_ENABLE_OCAMLDOC "Build OCaml bindings documentation." ON)
 
 option (LLVM_BUILD_EXTERNAL_COMPILER_RT
   "Build compiler-rt as an external project." OFF)
 
 # You can configure which libraries from LLVM you want to include in the
 # shared library by setting LLVM_DYLIB_COMPONENTS to a semi-colon delimited
 # list of LLVM components. All component names handled by llvm-config are valid.
 if(NOT DEFINED LLVM_DYLIB_COMPONENTS)

docs/CMakeLists.txt

if (SPHINX_FOUND)
     if (${SPHINX_OUTPUT_MAN})
       add_sphinx_target(man llvm)
     endif()
 
   endif()
 endif()
 
 list(FIND LLVM_BINDINGS_LIST ocaml uses_ocaml)
-if( NOT uses_ocaml LESS 0 )
+if( NOT uses_ocaml LESS 0 AND LLVM_ENABLE_OCAMLDOC )
   set(doc_targets
         ocaml_llvm
         ocaml_llvm_all_backends
         ocaml_llvm_analysis
         ocaml_llvm_bitreader
         ocaml_llvm_bitwriter
         ocaml_llvm_executionengine
         ocaml_llvm_irreader