OpenJDK11 build on macOS with autoconf 2.72 / -std=gnu++11 option

[Baesken, Matthias]

Btw. Is there already something  at make/autoconf that does similar filtering of unwanted flags ?
The mentioned TOOLCHAIN_POST_DETECTION  seems just to reset some variables  like CXX_CFLAGS to old values ,  not sure if  this is what we want here ?


>Hi Erik, I created  :
>
>https://bugs.openjdk.org/browse/JDK-8323008
>8323008: filter out any -std* flags added by autoconf from CC/CXX
>
>Feel free to add  additional info  to this JBS issue  .
>