clang: Upgrade to 20.1.6 minor release

clang: Upgrade to 20.1.6 minor release

Brings following commits

* 47addd4540b4 [libclc] Include isnan implementation for SPIR-V targets
* 4b6e5a286653 [clang-format] Handle Java text blocks (#141334)
* 0e1ef696f1fe [Driver] Fix _XOPEN_SOURCE definition on Solaris (#137141)
* 5d99a97583e1 [MachO] Improve bounds check (#141083)
* aa804fd3e624 [sanitizer_common] Remove interceptors for deprecated struct termio (#137403)
* 53393e26d5f4 [LoongArch] Prevent R0/R1 allocation for rj operand of [G]CSRXCHG (#140862)
* 6fcb1c127b40 [LoongArch] Fix assertion failure for annotate tablejump (#140907)
* 15ec590e389b release/20.x: [clang-format] Fix the indent of StartOfName after AttributeMacro (#140361)
* 802f4f75372e [clang-format] Handle raw string literals containing JSON code (#140666)
* 9b0832508ede [SDAG] Ensure load is included in output chain of sincos expansion (#140525)
* 8a36b8e3ab46 [clang][analyzer] Handle CXXParenInitListExpr alongside InitListExpr
* 070cf62530ea [Clang] Demote mixed enumeration arithmetic error to a warning (#131811)
* a169f5ca4e4f Correct position of CFI Instruction for Pointer Authentication"
* 5befd1fb3c97 [Clang][AST] Fix HandleLValueBase to deal with references (#140105)
* e3d2c00ccee4 [LLD][COFF] Allow -arm64xsameaddress in ARM64EC directives (#139631)
* 85e06a761483 [LoongArch] Fix fp_to_uint/fp_to_sint conversion errors for lasx (#137129)
* ff2e8f93f609 Fix test pfalse-v4i1.ll added in #138712 to require asserts.
* 1e4d39e07757 Bump version to 20.1.6

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>