Fix common misspellings

Fixes generated by 'codespell' and manually reviewed.

Signed-off-by: Lucas De Marchi <lucas.demarchi@profusion.mobi>
diff --git a/lib/bitmap.c b/lib/bitmap.c
index 741fae9..91e0ccf 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -830,7 +830,7 @@
  *  @orig (i.e. bits 3, 5, 7 and 9) were also set.
  *
  *  When bit 11 is set in @orig, it means turn on the bit in
- *  @dst corresponding to whatever is the twelth bit that is
+ *  @dst corresponding to whatever is the twelfth bit that is
  *  turned on in @relmap.  In the above example, there were
  *  only ten bits turned on in @relmap (30..39), so that bit
  *  11 was set in @orig had no affect on @dst.
diff --git a/lib/btree.c b/lib/btree.c
index c9c6f03..2a34392 100644
--- a/lib/btree.c
+++ b/lib/btree.c
@@ -11,7 +11,7 @@
  * see http://programming.kicks-ass.net/kernel-patches/vma_lookup/btree.patch
  *
  * A relatively simple B+Tree implementation.  I have written it as a learning
- * excercise to understand how B+Trees work.  Turned out to be useful as well.
+ * exercise to understand how B+Trees work.  Turned out to be useful as well.
  *
  * B+Trees can be used similar to Linux radix trees (which don't have anything
  * in common with textbook radix trees, beware).  Prerequisite for them working
@@ -541,7 +541,7 @@
 	int i, no_left, no_right;
 
 	if (fill == 0) {
-		/* Because we don't steal entries from a neigbour, this case
+		/* Because we don't steal entries from a neighbour, this case
 		 * can happen.  Parent node contains a single child, this
 		 * node, so merging with a sibling never happens.
 		 */
diff --git a/lib/decompress_unxz.c b/lib/decompress_unxz.c
index cecd23d..9f34eb5 100644
--- a/lib/decompress_unxz.c
+++ b/lib/decompress_unxz.c
@@ -83,7 +83,7 @@
  *    safety_margin = 128 + uncompressed_size * 8 / 32768 + 65536
  *                  = 128 + (uncompressed_size >> 12) + 65536
  *
- * For comparision, according to arch/x86/boot/compressed/misc.c, the
+ * For comparison, according to arch/x86/boot/compressed/misc.c, the
  * equivalent formula for Deflate is this:
  *
  *    safety_margin = 18 + (uncompressed_size >> 12) + 32768
diff --git a/lib/parser.c b/lib/parser.c
index 6e89eca..dcbaaef 100644
--- a/lib/parser.c
+++ b/lib/parser.c
@@ -13,7 +13,7 @@
 
 /**
  * match_one: - Determines if a string matches a simple pattern
- * @s: the string to examine for presense of the pattern
+ * @s: the string to examine for presence of the pattern
  * @p: the string containing the pattern
  * @args: array of %MAX_OPT_ARGS &substring_t elements. Used to return match
  * locations.
diff --git a/lib/timerqueue.c b/lib/timerqueue.c
index e3a1050..191176a 100644
--- a/lib/timerqueue.c
+++ b/lib/timerqueue.c
@@ -5,7 +5,7 @@
  *  Uses rbtrees for quick list adds and expiration.
  *
  *  NOTE: All of the following functions need to be serialized
- *  to avoid races. No locking is done by this libary code.
+ *  to avoid races. No locking is done by this library code.
  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License as published by