Fix a/an usage

man2/epoll_wait.2

@@ -85,7 +85,7 @@ struct epoll_event {
 
 The
 .I data
-of each returned structure will contain the same data the user set with a
+of each returned structure will contain the same data the user set with an
 .BR epoll_ctl (2)
 .RB ( EPOLL_CTL_ADD , EPOLL_CTL_MOD )
 while the

man3/ecvt.3

@@ -51,7 +51,7 @@ _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 500
 The
 .BR ecvt ()
 function converts \fInumber\fP to a null-terminated
-string of \fIndigits\fP digits (where \fIndigits\fP is reduced to an
+string of \fIndigits\fP digits (where \fIndigits\fP is reduced to a
 system-specific limit determined by the precision of a
 .IR double ),
 and returns a pointer to the string.

man3/scanf.3

@@ -294,9 +294,9 @@ or
 .B j
 As for
 .BR h ,
-but the next pointer is a pointer to a
+but the next pointer is a pointer to an
 .I intmax_t
-or
+or a
 .IR uintmax_t .
 This modifier was introduced in C99.
 .TP

man4/rtc.4

@@ -184,9 +184,9 @@ The periodic interrupt must be separately enabled or disabled using the
 requests.
 The third
 .BR ioctl (2)
-argument is a
+argument is an
 .I "unsigned long\ *"
-or a
+or an
 .IR "unsigned long" ,
 respectively.
 The value is the frequency in interrupts per second.