consistency: Use exported variables of required tools

We check for apps:

* make
* sed
* grep
* awk
* libtool/libtoolize
* install
* patch
* and more

...during configure. Our scripts should be consistent about using the
variables that define where the found tool was found.

Of course, we do hard-link these tools in buildtools, but that should be
a backup for the components we are building. Our scripts should always
use the tools we find.

Signed-off-by: Bryan Hundven <bryanhundven@gmail.com>

scripts/functions

@@ -478,7 +478,7 @@ CT_DoForceRmdir() {
 # Echoes the specified string on stdout until the pipe breaks.
 # Doesn't fail
 # $1: string to echo
-# Usage: CT_DoYes "" |make oldconfig
+# Usage: CT_DoYes "" |${make} oldconfig
 CT_DoYes() {
     yes "$1" || true
 }
@@ -1117,7 +1117,7 @@ CT_Patch() {
         if [ -n "${d}" -a -d "${d}" ]; then
             for p in "${d}"/*.patch; do
                 if [ -f "${p}" ]; then
-                    CT_DoExecLog ALL patch --no-backup-if-mismatch -g0 -F1 -p1 -f -i "${p}"
+                    CT_DoExecLog ALL ${patch} --no-backup-if-mismatch -g0 -F1 -p1 -f -i "${p}"
                 fi
             done
             if [ "${CT_PATCH_SINGLE}" = "y" ]; then
@@ -1363,7 +1363,7 @@ CT_DoSaveState() {
     # We must omit shell functions, and some specific bash variables
     # that break when restoring the environment, later. We could do
     # all the processing in the awk script, but a sed is easier...
-    set |awk '
+    set |${awk} '
               BEGIN { _p = 1; }
               $0~/^[^ ]+ \(\)/ { _p = 0; }
               _p == 1