BUG: PeriodIndex fails to handle NA, rather than putting NaT in its place (pandas-dev#46673)

Author: kapiliyer

pandas/_libs/tslibs/period.pyx

@@ -72,7 +72,6 @@ from pandas._libs.tslibs.timedeltas cimport (
 
 from pandas._libs.tslibs.conversion import DT64NS_DTYPE
 
-from pandas._libs.missing cimport C_NA
 from pandas._libs.tslibs.dtypes cimport (
     FR_ANN,
     FR_BUS,