bytecmp: preserve the identity for literal objects
When a literal appears in the file multiple times its identity should be preserved. CLHS 220.127.116.11: > If two literal objects appearing in the source code for a single > file processed with the file compiler are the identical, the > corresponding objects in the compiled code must also be the identical. Previously, every bytecode object created during ext::bc-compile-file had its own vector of constants making it impossible to satisfy this constraint. Thus, we change ext::bc-compile-file to use the same constants vector for all bytecode objects from the same file. The simplest way to achieve this is to use the same compiler environment for all of the compilation process and push the read-compile loop into the si_bc_compile_from_stream function implemented in C.