It seems that on iOS, where we don't have any Java, Python, BASIC, or
other scripting, the only thing that would use the C++/UNO bridge
functionality that invokes codeSnippet() was cppu::throwException().

codeSnippet() is part of what corresponds to the code that uses
run-time-generated machine code on other platforms. We can't generate
code at run-time on iOS, that has been known forever. Instead we have
used some manually written assembler to handle it instead. We used to
have a Perl script to generate a set of code snippets for different
cases, different numbers of parameters of the called function and
whatnot, but that went away at some stage some year ago. (It is
unclear whether that broke the C++/UNO bridge on iOS, or whether the
stuff continued to work even after that.)

Anyway, this handwritten assembly, or the manual construction of
internal data structures for exceptions, or something else, seemed to
have bit-rotten. Exceptions thrown with cppu::throwException() were
not catchable properly any longer.

Instead of digging in and trying to understand what is wrong, I chose
another solution. It turns out that the number of types of exception
objects thrown by cppu::throwException() is fairly small. During
startup of the LibreOffice code, and loading of an .odt document, only
one kind of exception is thrown this way... (The lovely
css::ucb:InteractiveAugmentedIOException.)

So we can simply have code that checks what the type of object being
thrown is, and explicitgly throws such an object then with a normal
C++ throw statement. Seems to work.

Sadly the cppu::getCaughtException() API still needs some inline
assembly in the C++/UNO brige. That seems to work though, knock on
wood.

This commit also adds a small "unit test" for iOS, copied from
cppuhelperm to ImplSVMain(). Ideally we should not copy code around of
course, but have a separate unit test app for iOS that would somehow
include relevant unit tests from source files all over the place.
Later.

Change-Id: Ib6d9d5b6fb8cc684ec15c97a312ca2f720e87069
Reviewed-on: https://gerrit.libreoffice.org/60506
Tested-by: Jenkins
Reviewed-by: Tor Lillqvist <tml@collabora.com>