Fix SPIR-V reserved ranges (KhronosGroup#427)

The unused portions hadn't been updated so were overlapping the reserved
ranges.

Author: gnl21

include/spirv/spir-v.xml

@@ -157,7 +157,7 @@
          sure to fill in the vendor attribute, and preferably add a contact
          person/address in a comment attribute. -->
     <!-- Example new block: <ids type="opcode" start="XXXX" end="XXXX+64n-1" vendor="Add vendor" comment="Contact TBD"/> -->
-    <ids type="opcode" start="6656" end="65535" comment="Opcode range reservable for future use by vendors"/>
+    <ids type="opcode" start="6720" end="65535" comment="Opcode range reservable for future use by vendors"/>
     <!-- End reservations of opcodes -->
 
 
@@ -190,7 +190,7 @@
          sure to fill in the vendor attribute, and preferably add a contact
          person/address in a comment attribute. -->
     <!-- Example new block: <ids type="enumerant" start="XXXX" end="XXXX+64n-1" vendor="Add vendor" comment="Contact TBD"/> -->
-    <ids type="enumerant" start="6656" end="4294967295" comment="Enumerant range reservable for future use by vendors"/>
+    <ids type="enumerant" start="6720" end="4294967295" comment="Enumerant range reservable for future use by vendors"/>
     <!-- End reservations of enumerants -->