Merge pull request #7481 from pgavlin/RyuJITCrossgen

Add an option to crossgen S.P.CoreLib using the alt jit.

diff --cc build.cmd
index c1f3144,69026de..ad603db
--- 1/build.cmd
--- 2/build.cmd
+++ b/build.cmd
@@@ -105,8 -103,8 +105,9 @@@ if /i "%1" == "skiptests"           (se
  if /i "%1" == "skipbuildpackages"   (set __BuildPackages=0&set processedArgs=!processedArgs! %1&shift&goto Arg_Loop)
  if /i "%1" == "usenmakemakefiles"   (set __NMakeMakefiles=1&set __ConfigureOnly=1&set __BuildNative=1&set __BuildNativeCoreLib=0&set __BuildCoreLib=0&set __BuildTests=0&set __BuildPackages=0&set processedArgs=!processedArgs! %1&shift&goto Arg_Loop)
  if /i "%1" == "buildjit32"          (set __BuildJit32="-DBUILD_JIT32=1"&set processedArgs=!processedArgs! %1&shift&goto Arg_Loop)
 +if /i "%1" == "pgoinstrument"       (set __PgoInstrument=1&set processedArgs=!processedArgs! %1&shift&goto Arg_Loop)
  if /i "%1" == "toolset_dir"         (set __ToolsetDir=%2&set __PassThroughArgs=%__PassThroughArgs% %2&set processedArgs=!processedArgs! %1 %2&shift&shift&goto Arg_Loop)
+ if /i "%1" == "altjitcrossgen"      (set __AltJitCrossgen=1&set processedArgs=!processedArgs! %1&shift&goto Arg_Loop)
  
  if [!processedArgs!]==[] (
    call set __UnprocessedBuildArgs=!__args!