llvm-10.0: update script to include riscv64 target

Bug: b/217573066
Signed-off-by: Rebecca Chang Swee Fun <rebecca.chang@starfivetech.com>
Change-Id: Ied6840b43065f281fde4a4ccb85296e818b1cb35
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/64669
Kokoro-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Ben Clayton <bclayton@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>

third_party/llvm-10.0/scripts/update.py

diff --git a/third_party/llvm-10.0/scripts/update.py b/third_party/llvm-10.0/scripts/update.py
index d25eecf..f6cf4bf 100644
--- a/third_party/llvm-10.0/scripts/update.py
+++ b/third_party/llvm-10.0/scripts/update.py
@@ -46,6 +46,7 @@
     ('X86', ('__i386__', '__x86_64__')),
     ('Mips', ('__mips__',)),
     ('PowerPC', ('__powerpc64__',)),
+    ('RISCV', ('__riscv',)),
 ]
 
 # Per-platform arches
@@ -64,6 +65,7 @@
         ('__mips__', 'mipsel-linux-gnu'),
         ('__mips64', 'mips64el-linux-gnuabi64'),
         ('__powerpc64__', 'powerpc64le-unknown-linux-gnu'),
+        ('__riscv', 'riscv64-unknown-linux-gnu'),
     ],
     'darwin': [
         ('__x86_64__', 'x86_64-apple-darwin'),