Redefinition of typedefs (C11 feature)

[Eduardo Habkost]

I'm wondering: do our supported build host platforms all include
compilers that are new enough to let us redefine typedefs?

The ability to redefine typedefs is a C11 feature which would be
very useful for simplifying our QOM boilerplate code.  The
feature is supported by GCC since 2011 (v4.6.0)[1], and by clang
since 2012 (v3.1)[2].

[1] 
https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=ce3765bf44e49ef0568a1ad4a0b7f807591d6412
    https://gcc.gnu.org/gcc-4.6/changes.html
[2] 
https://github.com/llvm-mirror/clang/commit/c0004df84fca9225b66a50adc66cf21c34298227

-- 
Eduardo