[runtime]Properly calculate the bitmap of valuetype [ThreadStatic] variables.

We must account that a valuetype field offset is relative to a boxed instance
and TLS memory stores a valuetype unboxed.
Add a --with-llvm=<llvm prefix> argument to configure to make the location of llvm-config explicit, instead of reading it from the PATH, which might be different on a reconfigure.
Move mono_get_optimizations_for_method to mini.c, since driver.c is only included in binaries, not libraries.
Add OrderedDictionary to the mobile profile.

Requested in support case #49635.
Prefix internal variables with `mono_`.