Fix build issue in libkholidays

Signed-off-by: François Andriot <francois.andriot@free.fr>

libkholidays/scanholiday.c

@@ -8,7 +8,6 @@
 #define yy_flush_buffer kcal_flush_buffer
 #define yy_load_buffer_state kcal_load_buffer_state
 #define yy_switch_to_buffer kcal_switch_to_buffer
-#define yyin kcalin
 #define yyleng kcalleng
 #define yylex kcallex
 #define yyout kcalout