Change "as" to "clang" in all examples

[below]

"The stand-alone system assemblers for i386, x86_64, and arm are deprecated and may be removed in a future Xcode release. Using the as command with the -Q flag shows a warning that instructs you to transition to Clang’s integrated assembler and the -q flag. The as(1) driver will remain, as a standard way to invoke Clang’s integrated assembler, as well as any assemblers installed by the developer. (61299833)"

[below]

Changed gcc, will leave as