Use size of pointer for offset #97

Job	Run time
abi-dump-setup	52s
Test llvm,clang,libclc / Lit Tests (ubuntu-latest)	45m 41s
Test lld / Lit Tests (ubuntu-latest)	10m 14s
Test llvm,clang,libclc / Lit Tests (windows-2019)	1m 28s
Build lldb / Lit Tests (ubuntu-latest)	24m 34s
Test lld / Lit Tests (windows-2019)	1m 28s
Test llvm,clang,libclc / Lit Tests (macOS-latest)	6h 0m 2s
Build lldb / Lit Tests (windows-2019)	1m 35s
Test lld / Lit Tests (macOS-latest)	1h 40m 50s
Build lldb / Lit Tests (macOS-latest)	5m 11s
abi-dump (build-baseline)	31m 44s
abi-dump (build-latest)	32m 14s
abi-compare	32s
	10h 16m 25s

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