forbid common symbols globally
add more libcxx things, partially partially

 * __bit_reference
 * __functional_03
 * __functional_base_03
 * __hash_table
 * __split_buffer
 * __tree
 * __tuple_03
 * algorithm
 * array
 * bitset
 * complex
 * cstdio
 * deque
 * forward_list
 * functional
 * list
 * map
 * memory
 * queue
 * random
 * set
 * stack
 * stdexcept
 * string
 * system_error
 * unordered_map
 * unordered_set
 * vector
prefer integer_sequence over custon list of integral_constants
undo some not-as-useful libc customizations
move ense (de)allocation functions to memalloc.cpp, fix new(size_t)
generate linker script with cpp

this will be useful for linking with gold.
move ivt/memalloc_regions around while at it.
remove owner pointers from memalloc blocks
generate dependency info while compiling
remove useless .target file stuff