Fix release/export.sh to export runtimes tarball, too (#67404)

This addresses missing cmake files needed to build some sub-projects
like libstdcxx.

Co-authored-by: René Rebe <[email protected]>

Author: rxrbln

llvm/utils/release/export.sh

@@ -13,7 +13,7 @@
 
 set -e
 
-projects="llvm bolt clang cmake compiler-rt libcxx libcxxabi libclc clang-tools-extra polly lldb lld openmp libunwind mlir flang third-party"
+projects="llvm bolt clang cmake compiler-rt libcxx libcxxabi libclc clang-tools-extra polly lldb lld openmp libunwind mlir flang runtimes third-party"
 
 release=""
 rc=""