[llvm] [SYCL] Add libsycl, a SYCL RT library implementation project (PR #144372)

[Kseniya Tikhomirova via llvm-commits]

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@@ -46,6 +53,9 @@ This requires at least partial support of the following functionality on the lib
   * Unified shared memory allocation/deallocation
   * Program manager, an internal component for retrieving and using device images from the multi-architectural binaries
 
+Builds steps
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KseniyaTikhomirova wrote:

updated https://github.com/llvm/llvm-project/pull/144372/commits/2caf523093e0c16b22a0af8c680ca2835504557e

https://github.com/llvm/llvm-project/pull/144372