ada: Remove redundant parentheses inside unary operators

GNAT already emits a style warning when redundant parentheses appear inside
logical and short-circuit operators. A similar warning will be soon emitted for
unary operators as well. This patch removes the redundant parentheses to avoid
future build errors.

gcc/ada/ChangeLog:

	* checks.adb, exp_dist.adb, exp_imgv.adb, exp_util.adb,
	libgnarl/a-reatim.adb, libgnat/a-coinve.adb, libgnat/a-nbnbre.adb,
	libgnat/a-ngcoty.adb, libgnat/a-ngelfu.adb, libgnat/a-ngrear.adb,
	libgnat/a-strbou.ads, libgnat/a-strfix.ads, libgnat/a-strsea.adb,
	libgnat/a-strsea.ads, libgnat/a-strsup.ads,
	libgnat/a-strunb__shared.ads, libgnat/g-alleve.adb,
	libgnat/g-spitbo.adb, libgnat/s-aridou.adb, libgnat/s-arit32.adb,
	libgnat/s-dourea.ads, libgnat/s-genbig.adb, libgnat/s-imager.adb,
	libgnat/s-statxd.adb, libgnat/s-widthi.adb, sem_attr.adb, sem_ch10.adb,
	sem_ch3.adb, sem_ch6.adb, sem_ch7.adb, sem_dim.adb, sem_prag.adb,
	sem_res.adb, uintp.adb: Remove redundant parentheses inside NOT and ABS
	operators.