Add some more headers.

This patch adds trivial implementations of the missing sys headers
needed by strace. All strace needs are the constants and structures,
so this is enough for now. We can come back and add the functions
if/when we ever need them.

Change-Id: Idb87c1a8b6b1c62f6e16ae94f147e1169722b48e
Add -Bsymbolic to the ld flags when linking the dynamic linker.

We don't need this on architectures other than aarch64, and
we're still investigating why we need it on aarch64, but it
doesn't seem unreasonable to have this flag set when linking
the dynamic linker anyway; it's clearly the intended behavior.

Change-Id: I4fa1b4ae543a818979934bf818eabac03bb9154f
Fix libdl build warnings, turn on -Werror.

Change-Id: I71c39b77ac1e9a92482ce71a829449100945ec86

Conflicts:
	libdl/libdl.c
Add "__noreturn" to assert and assert2

These functions should print assertion violation messages and then
call abort(). They do really not return control flow afterwards.
Consider the declaration of the similar __assert_fail from glibc:

extern void __assert_fail (const char *__assertion,
                           const char *__file,
			   unsigned int __line,
                           const char *__function)
     __THROW __attribute__ ((__noreturn__));

Bionic has __noreturn defined in sys/cdefs.h to be that GNU
noreturn attribute.

This patch has a practical value. Consider the following function:

void check(void* ptr) {
  assert(ptr != NULL);
}

Without this patch applied, gcc (and presumably clang) shows even in
debug mode:

warning: unused parameter 'ptr' [-Wunused-parameter]

In release mode, NDEBUG is defined and assert() becomes a no-op, as
one should expect. Thus, the warning is shown correctly then.

Another code sample:

float array[2];
int i = 3;
...
assert(i < 2);
array[i] = 0;

gcc says,

warning: array subscript is below array bounds [-Warray-bounds]

In other words, without noreturn attribute, assertions do not
allow a compiler's static analyzer to properly understand
the preconditions.

Change-Id: I3be92e99787c528899cf243ed448c4730c00c45b
Signed-off-by: Vadim Markovtsev <gmarkhor@gmail.com>