target/ppc: Increment PMC5 with inline insns

target/ppc: Increment PMC5 with inline insns

Profiling QEMU during Fedora 35 for PPC64 boot revealed that
6.39% of total time was being spent in helper_insns_inc(), on a
POWER9 machine. To avoid calling this helper every time PMCs had
to be incremented, an inline implementation of PMC5 increment and
check for overflow was developed. This led to a reduction of
about 12% in Fedora's boot time.

Signed-off-by: Leandro Lupori <leandro.lupori@eldorado.org.br>
Reviewed-by: Daniel Henrique Barboza <danielhb413@gmail.com>
Message-Id: <20221025202424.195984-4-leandro.lupori@eldorado.org.br>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>