Upgrade cctools unexpectedly failing

[Ken Cunningham]

> I wonder if the SDK path is
> baked into llvm-config-mp-7.0?


Yep -- sheesh. Is there no end to this?

Ken

$ llvm-config-mp-7.0 --cflags
-I/opt/universalnew/libexec/llvm-7.0/include -pipe -Os -isysroot/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.13.sdk -fPIC -Werror=date-time -Werror=unguarded-availability-new -Wall -Wextra -Wno-unused-parameter -Wwrite-strings -Wmissing-field-initializers -pedantic -Wno-long-long -Wcovered-switch-default -Wdelete-non-virtual-dtor -Wstring-conversion -DNDEBUG -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS