Spack compiler wrapper script. Compiler commands go through this compiler wrapper in Spack builds. The compiler wrapper is a thin layer around the standard compilers. It enables several key pieces of functionality: 1. It allows Spack to swap compilers into and out of builds easily. 2. It adds several options to the compile line so that spack packages can find their dependencies at build time and run time: -I and/or -isystem arguments for dependency /include directories. -L arguments for dependency /lib directories. -Wl,-rpath arguments for dependency /lib directories. 3. It provides a mechanism to inject flags from specs