[remote testsuite] Spurious failures

Some tests cases result in FAILs when running the testsuite remotely, because of bugs in the test case. These include:

gdb.stabs/gdb11479.exp
* Hard-codes "run" instead of starting execution in a compatible manner

gdb.base/break-entry.exp: running to *0x8150 in runto
gdb.base/nostdlib.exp: stop at run
gdb.base/nostdlib.exp: continue to marker
* Attempt to run to entry point even though in remote mode, we already start out there

gdb.cp/exception.exp: continue to second throw
* Attempts to verify inferior stdout, even though this is not supported remotely

gdb.base/watch-vfork.exp: Watchpoint triggers after vfork (sw)
gdb.threads/execl.exp
gdb.threads/fork-child-threads.exp
* Require fork/exec catchpoints, which are not supported remotely

gdb.mi/mi-var-cmd.exp: in-and-out-of-scope: in scope now
* Relies on address space randomization being disabled, which is not supported by gdbserver

These need to be fixed where (easily) possible, or else the test needs to be skipped when running remotely.