pseudo: Remove 64bit time_t flags

pseudo traps syscalls and has intimate knowledge of them
and does not really depend on glibc interfaces to kernel

flags are added via TARGET_CC_ARCH therefore move the remove
operation from TARGET_CPPFLAGS to TARGET_CC_ARCH

Signed-off-by: Khem Raj <raj.khem@gmail.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>