Remove RISCV from LLVM_ALL_TARGETS in CMakeLists.txt

[asb]

Summary

It was mistakenly added to that list in D23560 (committed in rL285712). RISCV is an experimental backend and should never have been in that list, I mistakenly interpreted LLVM_ALL_TARGETS as a list of all targets rather than targets to build by default. Unfortunately, because of this the RISCV backend has been building by default when it shouldn't be.

Please see my message to llvm-dev for more info and analysis.

[emaste]

Adding the comment above the list seems like a good idea to me.

[grosser]

seems very reasonable to me

[hans]

Looks good to me.

CMakeLists.txt

 set(LLVM_MAIN_INCLUDE_DIR ${LLVM_MAIN_SRC_DIR}/include ) # --includedir
 set(LLVM_BINARY_DIR       ${CMAKE_CURRENT_BINARY_DIR}  ) # --prefix
 
 # Note: LLVM_CMAKE_PATH does not include generated files
 set(LLVM_CMAKE_PATH ${LLVM_MAIN_SRC_DIR}/cmake/modules)
 set(LLVM_EXAMPLES_BINARY_DIR ${LLVM_BINARY_DIR}/examples)
 set(LLVM_INCLUDE_DIR ${CMAKE_CURRENT_BINARY_DIR}/include)
 
+# List of all targets to be built by default:
 set(LLVM_ALL_TARGETS
   AArch64
   AMDGPU
   ARM
   BPF
   Hexagon
   Lanai
   Mips
   MSP430
   NVPTX
   PowerPC
-  RISCV
   Sparc
   SystemZ
   X86
   XCore
   )
 
 # List of targets with JIT support:
 set(LLVM_TARGETS_WITH_JIT X86 PowerPC AArch64 ARM Mips SystemZ)