[aslr-analysis] Switch to fdio_spawn_etc

Most codepaths that create processes should use fdio_spawn rather than
launchpad directly.

Test: Manually ran aslr-analysis

Change-Id: I818e2142ba332f7b6ed123aca4acf35aa2690b81

[zx] Magenta -> Zircon

The Great Renaming is here!

Change-Id: I3229bdeb2a3d0e40fb4db6fec8ca7d971fbffb94

[zircon][mxtl->fbl] Rename mxtl to fbl

Change-Id: Ie21b6498e1bfb0a7fa0315e40b9e5c3ee78646be

[build][groups] annotate 'misc' and 'test' modules

This allows us to generate a bootdata.bin which excludes them,
reducing it from 4.52MB to 2.65MB

The default bootdata.bin still includes all modules.

Change-Id: If13bfcacba9386a691e6b7c380eed53d67bb44eb

[ulib] Make mxtl, mxcpp, and mx libraries static-only

mxtl is actually a header-only library, so don't build a
shared object for it.

The mxtl and mx libraries are already built only as static
libraries in the Fuchsia GN build. Their code is very small.
Make the Magenta make build follow suit.

Change-Id: Ia79e5a996a981a8b046370d4ece9597f8e5bd1c2

[build] flatten the build

Previously we treated kernel/, system/, and third_party/ as
overlays on a shared namespace. This required the concept
of "canonical" module names, and a lot of complexity to ensure
that things didn't collide and the build worked.

This change gets rid of that, no longer passes -I to make,
so that include directives from our *.mk files do not magically
wildcard across various paths, etc.

The most user-visible change is that everywhere where a module
name is specified (MODULE_DEPS, MODULE_LIBS, etc), full module
names like kernel/lib/io or system/ulib/mxio must be used instead
of previously-allowed "short" names like lib/io and ulib/mxio.

The build output still has a similar shape, but the first segment
of the module path (kernel/, system/, or third_party/) is no
longer elided under $(BUILDDIR)

Change-Id: I525aba1da1c86eb7a86007bddc669f7eeebfedd5

[system] Fix headers that weren't using a BSD license

Change-Id: I4a0f6fd14d207cc243b6f41e5cb6d7676052d63b

[build][musl] refer to musl libc as ulib/c

This makes the build rules and the intermediate
output files easier to understand, without having
to modify the path where musl libc lives.

The biggest observeable difference is the build
intermediate files:

$ ls build-magenta-pc-x86-64/ulib/c
config-module.h libc.abi.h libc.abi.stamp libc.so libc.so.id libc.so.strip
libc.a libc.abi.o libc.a.opts libc.so.abi libc.so.opts third_party

which previously were at build-magenta-pc-x86/ulib/musl
and named libmusl.*

and the replacing of ulib/musl with ulib/c in the library
dependencies of all the rules.mk files (the vast bulk of
this change)

Change-Id: If9c5d522099d2c9ac5bdb666b8e67a2eb3d316ee

[uapp][aslr] Add app to perform a rough randomness estimation

This isn't a great measure, but it should provide an upper bound on
the effectiveness of our randomization. It currently does not test
for correlations between bits in an address or between measured
spaces.

Change-Id: I708c883be9ad6dbe33605bca383596e9721e23a6