Revert "Replace CMAKE_SYSROOT_FLAG with a lang specific COMPILE_OPTION."

This reverts commit 1dd9dd2c0b626ac011d792f7711bc7c5c2dbfc01.
Merge topic 'replace-CMAKE_SYSROOT_FLAG' into next

86707de Revert "Replace CMAKE_SYSROOT_FLAG with a lang specific COMPILE_OPTION."
Revert "Use --sysroot when cross compiling."

This reverts commit de4da665d3205afa239749c41513a315c3831f51.

This feature is not yet ready for release. It needs to be
merged with the CMAKE_OSX_SYSROOT feature.
Merge topic 'revert-CMAKE_SYSROOT' into next

0416c94 Revert "Use --sysroot when cross compiling."
Fix erroneous errors from the dashboard.

C:\Dashboards\My Tests\CMakeNMake60-src\Source\cmTarget.cxx(3449) : error C2562: 'processCompileOptions' : 'void' function returning a value
        C:\Dashboards\My Tests\CMakeNMake60-src\Source\cmTarget.cxx(3440) : see declaration of 'processCompileOptions'
C:\Dashboards\My Tests\CMakeNMake60-src\Source\cmTarget.cxx(3557) : error C2562: 'processCompileDefinitions' : 'void' function returning a value
        C:\Dashboards\My Tests\CMakeNMake60-src\Source\cmTarget.cxx(3548) : see declaration of 'processCompileDefinitions'
Merge topic 'compile-defs-debugging' into next

80bcc79 Fix erroneous errors from the dashboard.
Add target property debugging for COMPILE_DEFINITIONS

Use constructs similar to those for COMPILE_OPTIONS. This is a little
different because there is a command to remove_definitions(), so
we can't populate the equivalent target property until generate-time
in cmGlobalGenerator.
Merge topic 'compile-defs-debugging' into next

d7dd010 Add target property debugging for COMPILE_DEFINITIONS