Add support for PPC64 to LLVM update script

Update third_party/llvm-7.0/scripts/update.py to pull in PPC64 LLVM
sources.

Bug: b/135175069
Change-Id: I2d5d61a18b822d3a10d958e3d20d314f62d51226
Signed-off-by: Colin Samples <colin.samples+git@gmail.com>
Reviewed-on: https://swiftshader-review.googlesource.com/c/SwiftShader/+/32808
Reviewed-by: Nicolas Capens <nicolascapens@google.com>
Reviewed-by: Alexis Hétu <sugoi@google.com>
Presubmit-Ready: Nicolas Capens <nicolascapens@google.com>
Tested-by: Nicolas Capens <nicolascapens@google.com>
Kokoro-Presubmit: kokoro <noreply+kokoro@google.com>
diff --git a/third_party/llvm-7.0/scripts/update.py b/third_party/llvm-7.0/scripts/update.py
index 1a4e4f6..4f67353 100755
--- a/third_party/llvm-7.0/scripts/update.py
+++ b/third_party/llvm-7.0/scripts/update.py
@@ -34,6 +34,7 @@
     ('ARM', ('__arm__',)),
     ('X86', ('__i386__', '__x86_64__')),
     ('Mips', ('__mips__',)),
+    ('PowerPC', ('__powerpc64__',)),
 ]
 
 LLVM_TRIPLES = {
@@ -50,6 +51,7 @@
         ('__aarch64__', 'aarch64-linux-gnu'),
         ('__mips__', 'mipsel-linux-gnu'),
         ('__mips64', 'mips64el-linux-gnuabi64'),
+        ('__powerpc64__', 'powerpc64le-unknown-linux-gnu'),
     ],
     'darwin': [
         ('__x86_64__', 'x86_64-apple-darwin'),
@@ -122,6 +124,7 @@
         os.path.join('lib', 'Target', 'ARM'),
         os.path.join('lib', 'Target', 'X86'),
         os.path.join('lib', 'Target', 'Mips'),
+        os.path.join('lib', 'Target', 'PowerPC'),
         os.path.join('lib', 'Transforms', 'InstCombine'),
     ]
     for subdir in subdirs: