Fix some typos across the board

Found while browsing the code.

src/test/authentication/t/006_login_trigger.pl

@@ -144,7 +144,7 @@ psql_command(
 	err_like => [qr/You are welcome/]);
 
 # Try to login as allowed Alice.  We don't check the Mallory login, because
-# FATAL error could cause a timing-dependant panic of IPC::Run.
+# FATAL error could cause a timing-dependent panic of IPC::Run.
 psql_command(
 	$node, 'SELECT 1;', 0, 'try regress_alice',
 	connstr => 'user=regress_alice',

src/test/regress/expected/sysviews.out

@@ -29,7 +29,7 @@ select type, name, ident, level, total_bytes >= free_bytes
 (1 row)
 
 -- We can exercise some MemoryContext type stats functions.  Most of the
--- column values are too platform-dependant to display.
+-- column values are too platform-dependent to display.
 -- Ensure stats from the bump allocator look sane.  Bump isn't a commonly
 -- used context, but it is used in tuplesort.c, so open a cursor to keep
 -- the tuplesort alive long enough for us to query the context stats.

src/test/regress/sql/sysviews.sql

@@ -18,7 +18,7 @@ select type, name, ident, level, total_bytes >= free_bytes
   from pg_backend_memory_contexts where level = 1;
 
 -- We can exercise some MemoryContext type stats functions.  Most of the
--- column values are too platform-dependant to display.
+-- column values are too platform-dependent to display.
 
 -- Ensure stats from the bump allocator look sane.  Bump isn't a commonly
 -- used context, but it is used in tuplesort.c, so open a cursor to keep