patch 8.2.3315: cannot use single quote in a float number for readability

Problem:    Cannot use single quote in a float number for readability.
Solution:   Support single quotes like in numbers. (closes #8713)
diff --git a/src/proto/float.pro b/src/proto/float.pro
index 806eba1..cceb157 100644
--- a/src/proto/float.pro
+++ b/src/proto/float.pro
@@ -1,5 +1,5 @@
 /* float.c */
-int string2float(char_u *text, float_T *value);
+int string2float(char_u *text, float_T *value, int skip_quotes);
 void f_abs(typval_T *argvars, typval_T *rettv);
 void f_acos(typval_T *argvars, typval_T *rettv);
 void f_asin(typval_T *argvars, typval_T *rettv);