Update primary branch name for SPIR-V repos

`master` -> `main`.

Bug: none
Change-Id: I82e5c774588692452f2ede04516dc0905f4d22eb
diff --git a/third_party/update-spirvheaders.sh b/third_party/update-spirvheaders.sh
index 9985238..d1fc418 100755
--- a/third_party/update-spirvheaders.sh
+++ b/third_party/update-spirvheaders.sh
@@ -10,7 +10,7 @@
   REASON="\n$REASON\n"
 fi
 
-git subtree pull --prefix third_party/SPIRV-Headers https://github.com/KhronosGroup/SPIRV-Headers master --squash -m "Update SPIR-V Headers"
+git subtree pull --prefix third_party/SPIRV-Headers https://github.com/KhronosGroup/SPIRV-Headers main --squash -m "Update SPIR-V Headers"
 
 ALL_CHANGES=`git log -n 1 HEAD^2 | egrep '^(\s{4}[0-9a-f]{9}\s*.*)$'`
 HEAD_CHANGE=`echo "$ALL_CHANGES" | egrep '[0-9a-f]{9}' -o -m 1`
diff --git a/third_party/update-spirvtools.sh b/third_party/update-spirvtools.sh
index 931fe98..0cd19c0 100755
--- a/third_party/update-spirvtools.sh
+++ b/third_party/update-spirvtools.sh
@@ -12,7 +12,7 @@
 
 THIRD_PARTY_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}")" >/dev/null 2>&1 && pwd )"
 
-GIT_RESULT=`git subtree pull --prefix third_party/SPIRV-Tools https://github.com/KhronosGroup/SPIRV-Tools master --squash -m "Update SPIR-V Tools"`
+GIT_RESULT=`git subtree pull --prefix third_party/SPIRV-Tools https://github.com/KhronosGroup/SPIRV-Tools main --squash -m "Update SPIR-V Tools"`
 if [[ $GIT_RESULT == *"CONFLICT"* ]]; then
   echo "subtree pull resulted in conflicts. Atempting to automatically resolve..."
   # CONFLICT is very likely due to Android.mk being deleted in our third_party.