Update SPIRV-Headers to 204cd131c

Changes:
  204cd131c Merge pull request #134 from Tobski/patch-1
  e0adad52b Off-by-one errors
  6045738ac Reserve a new block of 64 opcodes

Commands:
  git subtree pull --prefix third_party/SPIRV-Headers https://github.com/KhronosGroup/SPIRV-Headers master --squash

Bug: b/123642959
Change-Id: I9389ad9ea7916464745c2dfedefe46e3ef3a52e4
diff --git a/third_party/SPIRV-Headers/include/spirv/spir-v.xml b/third_party/SPIRV-Headers/include/spirv/spir-v.xml
index 523460d..bcffd61 100644
--- a/third_party/SPIRV-Headers/include/spirv/spir-v.xml
+++ b/third_party/SPIRV-Headers/include/spirv/spir-v.xml
@@ -111,6 +111,7 @@
     <ids type="opcode" start="5696" end="5823" vendor="Intel" comment="Contact ben.ashbaugh@intel.com"/>
     <ids type="opcode" start="5824" end="5951" vendor="Intel" comment="Contact michael.kinsner@intel.com"/>
     <ids type="opcode" start="5952" end="6015" vendor="Codeplay" comment="Contact victor@codeplay.com"/>
+    <ids type="opcode" start="6016" end="6079" vendor="Khronos" comment="Contact @tobski"/>
     <!-- Opcodes & enumerants reservable for future use. To get a block, allocate
          multiples of 64 starting at the lowest available point in this
          block and add a corresponding <ids> tag immediately above. Make
@@ -119,7 +120,7 @@
 
     <!-- Example new block: <ids type="opcode" start="XXXX" end="XXXX+64n-1" vendor="Add vendor" comment="Contact TBD"/> -->
 
-    <ids type="opcode" start="6016" end="4294967295" comment="Opcode range reservable for future use by vendors"/>
+    <ids type="opcode" start="6080" end="4294967295" comment="Opcode range reservable for future use by vendors"/>
 
 
     <!-- SECTION: SPIR-V Loop Control Bit Reservations -->