Use SetInstallXLogFileSegmentActive() in more places in xlog.c

This reduces the code paths where XLogCtl->InstallXLogFileSegmentActive
is directly touched, and this wrapper function does the same thing as
the original code replaced by the function call.

Author: Bharath Rupireddy
Reviewed-by: Nathan Bossart
Discussion: https://postgr.es/m/CALj2ACVhkf-bC5CX-=6iBUfkO5GqmBntQH+m=HpY0iQ=-g1pRg@mail.gmail.com

Author: michaelpq

src/backend/access/transam/xlog.c

@@ -4501,9 +4501,7 @@ BootStrapXLOG(void)
 	pg_crc32c	crc;
 
 	/* allow ordinary WAL segment creation, like StartupXLOG() would */
-	LWLockAcquire(ControlFileLock, LW_EXCLUSIVE);
-	XLogCtl->InstallXLogFileSegmentActive = true;
-	LWLockRelease(ControlFileLock);
+	SetInstallXLogFileSegmentActive();
 
 	/*
 	 * Select a hopefully-unique system identifier code for this installation.
@@ -5368,9 +5366,7 @@ StartupXLOG(void)
 	 * Allow ordinary WAL segment creation before possibly switching to a new
 	 * timeline, which creates a new segment, and after the last ReadRecord().
 	 */
-	LWLockAcquire(ControlFileLock, LW_EXCLUSIVE);
-	XLogCtl->InstallXLogFileSegmentActive = true;
-	LWLockRelease(ControlFileLock);
+	SetInstallXLogFileSegmentActive();
 
 	/*
 	 * Consider whether we need to assign a new timeline ID.