`santactl fileinfo` should report incorrect signing ID for certain Xcode binaries

[russellhancox]

Some binaries that are part of Xcode are identified by ES as being platform binaries, even though codesign does not report them as having a "Platform Identifier".

E.g.

/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ld

santactl fileinfo reports the Signing ID for this binary as 59GAB85EFG:com.apple.ld

However, an ES event generated by this binary reports:

"is_platform_binary":true,"signing_id":"com.apple.ld","team_id":null.

MOLCodesignChecker's platformBinary property returns NO for these but does report the TeamID.

[mlw]

This seems like potentially a macOS issue. Filed FB: FB18568950