Runtimes: add -nostdlibimport to the runtime build

If the compiler being used to build the runtime is from a complete
toolchain, we may inadvertently pick up runtime from the previous build
rather than the just built Swift Core library. Pass `-nostdlibimport` to
ensure that we do not search the default search paths when building and
use the locally built swiftCore.

Author: compnerd

Runtimes/Core/Concurrency/CMakeLists.txt

@@ -90,6 +90,7 @@ target_compile_definitions(swift_Concurrency PRIVATE
   $<$<COMPILE_LANGUAGE:C,CXX>:-D__STDC_WANT_LIB_EXT1__=1>)
 target_compile_options(swift_Concurrency PRIVATE
   $<$<COMPILE_LANGUAGE:Swift>:-parse-stdlib>
+  $<$<COMPILE_LANGUAGE:Swift>:-nostdlibimport>
   # NOTE: do not remove until `IsolatedAny` is on by default in all supported
   # compilers.
   "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-enable-experimental-feature IsolatedAny>"

Runtimes/Core/SwiftOnoneSupport/CMakeLists.txt

@@ -11,6 +11,7 @@ endif()
 
 target_compile_options(swiftSwiftOnoneSupport PRIVATE
   $<$<COMPILE_LANGUAGE:Swift>:-parse-stdlib>
+  $<$<COMPILE_LANGUAGE:Swift>:-nostdlibimport>
   "$<$<COMPILE_LANGUAGE:Swift>:SHELL:-Xllvm -sil-inline-generics=false>"
 
   # We have to disable validation of TBD files, because this module is