[$] Yet another memory allocator for executable code

The kernel is an increasingly dynamic body of code, where new executabletext can show up at any time. Currently, the task of allocating memory fornew kernel code falls on the subsystem that first brought the ability toload code into a running kernel: the module loader. This patchset from Mike Rapoport looks to move the responsibility for theseallocations to a new "JIT allocator", addressing a number of rough edges inthe process.