tcg: Limit the number of ops in a TB

tcg: Limit the number of ops in a TB

In 6001f7729e12 we partially attempt to address the branch
displacement overflow caused by 15fa08f845.

However, gcc/testsuite/gcc.target/aarch64/advsimd-intrinsics/vqtbX.c
is a testcase that contains a TB so large as to overflow anyway.
The limit here of 8000 ops produces a maximum output TB size of
24112 bytes on a ppc64le host with that test case.  This is still
much less than the maximum forward branch distance of 32764 bytes.

Cc: qemu-stable@nongnu.org
Fixes: 15fa08f845 ("tcg: Dynamically allocate TCGOps")
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>