add guard in Formula#file_modified? to prevent git popup
add guard in Superenv.bin before calling MacOS::Xcode.version
add guard against missing Xcode/CLT in Xcode.uncached_version
return nil instread of 0 in uncached_version when Xcode/CLT are not present, to distinguish from linuxbrew behavior
checks against pour_bottle? and needs_relocation?, add guard around keg.relocate_install_names to check pour_bottle?/needs_relocation? as well
needs_relocation? becomes skip_relocation?, use cellar attr to indicate relocation instead of does_not_need_relocation
MacOS.can_build? becomes MacOS.has_apple_developer_tools?
For OS X, we will call `/usr/libexec/java_home` to exam whehter
java is installed.
Also rename the method to follow the same naming pattern of other
similar methods.
ClosesHomebrew/homebrew#36187.
Signed-off-by: Mike McQuaid <mike@mikemcquaid.com>