[llvm] [flang-rt][build] Disable two build-time warning of '-Wuninitialized' from g++ compiler (PR #174918)

[Eugene Epshteyn via llvm-commits]

eugeneepshteyn wrote:

> However, since GCC (and Clang, and msvc) is able to optimize-away the zero-initialization, I am strongly in favor of that workaround.

Which workaround? Are you proposing to zero-initialize these variables anyway and rely on gcc/clang/msvc to optimize it away?

https://github.com/llvm/llvm-project/pull/174918