android: fix LLVM version string related building errors

android: fix LLVM version string related building errors

Adding \ prior to " in llvm version string fixes the following building errors:

external/mesa/src/gallium/drivers/r600/r600_pipe_common.c:1290:14:
error: expected ')'
                 ", LLVM " MESA_LLVM_VERSION_STRING
                           ^
<command line>:8:34: note: expanded from here
                                 ^
external/mesa/src/gallium/drivers/r600/r600_pipe_common.c:1287:10:
note: to match this '('
        snprintf(rscreen->renderer_string, sizeof(rscreen->renderer_string),
                ^
1 error generated.

Fixes: 05b114e ("simplify LLVM version string printing")
Signed-off-by: Mauro Rossi <issor.oruam@gmail.com>
Reviewed-by: Eric Engestrom <eric@engestrom.ch>