[clang] [flang] [flang][windows] Add option to link against specific MSVC CRT (PR #70833)

[David Truby via cfe-commits]

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@@ -281,3 +281,26 @@ add_flang_library(FortranRuntime
 
   INSTALL_WITH_TOOLCHAIN
 )
+
+if (DEFINED MSVC)
+  set(CMAKE_MSVC_RUNTIME_LIBRARY MultiThreaded)
+  add_flang_library(FortranRuntime.static ${sources}
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DavidTruby wrote:

The plain FortranRuntime library is linked by the Runtime tests, which need to be built against whatever the user built LLVM with, which we can't necessarily find out that easily I think. It should not have INSTALL_WITH_TOOLCHAIN set though, I'll remove that

https://github.com/llvm/llvm-project/pull/70833