build: Add sh program property.
compiler: Forward executable and library target.
Formatting.
compiler: Add default OS env vars needed by the compiler.
compiler: Split add support for debug and optimization tuning.
dependency: Fix imports.
generators.makefile: Support multiple outputs.
compiler: Support import lib.
lang.c.gcc: Support for allow_unresolved_symbols flag.
Fix compat issues.
lang.c.msvc: Many improvements.
dependency.cmake: Add a CMake dependency builder.