Use size_t for Process offset values #4683

Job	Run time
build-ubuntu-latest-full-featured-clang	49s
build-ubuntu-latest-minimal-gcc	20s
build-freebsd-latest-clang	1m 56s
build-macos-latest-clang	46s
build-netbsd-latest-gcc	2m 43s
build-dragonflybsd-latest-gcc	2m 22s
build-ubuntu-latest-clang-analyzer	58s
build-ubuntu-latest-clang-sanitizer	59s
build-ubuntu-latest-full-featured-gcc	24s
build-ubuntu-latest-gcc-static	27s
build-ubuntu-latest-minimal-clang	46s
build-ubuntu-latest-pcp	26s
build-openbsd-latest-clang	2m 23s
build-solaris-latest-gcc	4m 47s
lint-pcp-config	3s
lint-whitespace	3s
	20m 12s

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