Fix #1924: Promote SPV_EXT_physical_storage_buffer to KHR when required.

If the semantics that require the KHR form over the EXT form are seen
(OpBitcast between a vector and a pointer) promote the requested extension
from the EXT to the KHR.

SPIRV/GlslangToSpv.cpp

@@ -6275,6 +6275,9 @@ spv::Id TGlslangToSpvTraverser::createConversion(glslang::TOperator op, OpDecora
         break;
     case glslang::EOpConvPtrToUvec2:
     case glslang::EOpConvUvec2ToPtr:
+        if (builder.isVector(operand))
+            builder.promoteIncorporatedExtension(spv::E_SPV_EXT_physical_storage_buffer,
+                                                 spv::E_SPV_KHR_physical_storage_buffer, spv::Spv_1_5);
         convOp = spv::OpBitcast;
         break;
 #endif