Should --with-build-sysroot be default to --with-sysroot?

[H.J. Lu]

When --with-sysroot is used to configure gcc, build will usually fail
if  --with-build-sysroot isn't set.  Should  --with-build-sysroot be set to
the same value as --with-sysroot by default if --with-sysroot is used?


-- 
H.J.