[CMake] Allow LLVM_EXTERNAL_<proj>_SOURCE_DIR to be overridden if it is
authorYuanfang Chen <yuanfang.chen@sony.com>
Fri, 26 Jul 2019 19:25:57 +0000 (19:25 +0000)
committerYuanfang Chen <yuanfang.chen@sony.com>
Fri, 26 Jul 2019 19:25:57 +0000 (19:25 +0000)
commitf184ce53a7cba35201e587cbf3a1a75d6a40a722
tree6c6d7f6b521374dba871a7768eccea3028f6c8a3
parentdeea000c915574a05b738a71a1b145951c64b5e6
[CMake] Allow LLVM_EXTERNAL_<proj>_SOURCE_DIR to be overridden if it is
empty.

This makes adding projects to LLVM_ENABLE_PROJECTS possible.
Also its type should be PATH.

https://bugs.llvm.org/show_bug.cgi?id=42698

Reviewers: beanz, greened, chapuni

Reviewed by: beanz

Differential Revision: https://reviews.llvm.org/D65045

llvm-svn: 367144
llvm/CMakeLists.txt