Fix spelling mistakes in comments in shell scripts

gdb/ChangeLog:
2016-11-22  Ambrogino Modigliani  <ambrogino.modigliani@gmail.com>

        * contrib/expect-read1.sh: Fix spelling in comments.
        * gdb_buildall.sh: Fix spelling in comments.
        * gdb_mbuild.sh: Fix spelling in comments.
diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 3257bae..2849067 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,11 @@
 2016-11-22  Ambrogino Modigliani  <ambrogino.modigliani@gmail.com>
 
+        * contrib/expect-read1.sh: Fix spelling in comments.
+        * gdb_buildall.sh: Fix spelling in comments.
+        * gdb_mbuild.sh: Fix spelling in comments.
+
+2016-11-22  Ambrogino Modigliani  <ambrogino.modigliani@gmail.com>
+
         * configure.ac: Fix spelling in comments.
         * configure: Regenerate.
 
diff --git a/gdb/contrib/expect-read1.sh b/gdb/contrib/expect-read1.sh
old mode 100644
new mode 100755
index cc9d811..5eec0dd
--- a/gdb/contrib/expect-read1.sh
+++ b/gdb/contrib/expect-read1.sh
@@ -15,7 +15,7 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-# This tool excercise any incomplete reads handling in the testsuite by
+# This tool exercises any incomplete reads handling in the testsuite by
 # simulating read always returns just 1 character.
 # Testsuite incompatibilities are tracked as GDB PR testsuite/12649.
 
diff --git a/gdb/gdb_buildall.sh b/gdb/gdb_buildall.sh
index 1fc7b38..ed3ffb5 100644
--- a/gdb/gdb_buildall.sh
+++ b/gdb/gdb_buildall.sh
@@ -103,7 +103,7 @@
 make=${MAKE:-make}
 MAKE=${make}
 export MAKE
-# We dont want GDB do dump cores.
+# We don't want GDB do dump cores.
 ulimit -c 0
 
 # Just make sure we're in the right directory.
diff --git a/gdb/gdb_mbuild.sh b/gdb/gdb_mbuild.sh
index 08927f1..da0c19a 100755
--- a/gdb/gdb_mbuild.sh
+++ b/gdb/gdb_mbuild.sh
@@ -195,7 +195,7 @@
 
 
 
-# Warn the user of what is comming, print the list of targets
+# Warn the user of what is coming, print the list of targets
 
 echo "$alltarg"
 echo ""
@@ -273,7 +273,7 @@
     then
 	# Iff the build fails remove the final build target so that
 	# the follow-on code knows things failed.  Stops the follow-on
-	# code thinking that a failed rebuild succedded (executable
+	# code thinking that a failed rebuild succeeded (executable
 	# left around from previous build).
 	echo ... ${make} ${keepgoing} ${makejobs} ${target}
 	( ${make} ${keepgoing} ${makejobs} all-gdb || rm -f gdb/gdb gdb/gdb.exe