tools/: Fix trivial typos.

tools/Makefile.unix

@@ -417,7 +417,7 @@ include tools/LibTargets.mk
 # pass1 and pass2
 #
 # If the 2 pass build option is selected, then this pass1 target is
-# configured to built before the pass2 target.  This pass1 target may, as an
+# configured to be built before the pass2 target.  This pass1 target may, as an
 # example, build an extra link object (CONFIG_PASS1_OBJECT) which may be an
 # incremental (relative) link object, but could be a static library (archive);
 # some modification to this Makefile would be required if CONFIG_PASS1_OBJECT
@@ -487,7 +487,7 @@ $(BIN): pass1deps pass2deps pass1 pass2
 # This is a helper target that will rebuild NuttX and download it to the target
 # system in one step.  The operation of this target depends completely upon
 # implementation of the DOWNLOAD command in the user Make.defs file.  It will
-# generate an error an error if the DOWNLOAD command is not defined.
+# generate an error if the DOWNLOAD command is not defined.
 
 download: $(BIN)
 	$(call DOWNLOAD, $<)

tools/sethost.sh

@@ -92,6 +92,7 @@ done
 #   Cygwin: CYGWIN_NT-10.0-WOW
 #   Linux: Linux
 #   MSYS: MINGW32_NT-6.2
+
 if [ -z "$host" ]; then
   case $(uname -s) in
     Darwin)
@@ -107,6 +108,7 @@ if [ -z "$host" ]; then
       ;;
     *)
       # Assume linux as a fallback
+
       host=linux
       ;;
   esac
@@ -122,7 +124,7 @@ fi
 if [ -x tools/sethost.sh ]; then
   nuttx=$PWD
 else
-  echo "This script must be execute in nuttx/ or nuttx/tools directories"
+  echo "This script must be executed in nuttx/ or nuttx/tools directories"
   exit 1
 fi