maint/util ~ remove extra/redundant factor tests for 'debug' builds

- avoids "Terminated" timeout errors when using longer running 'debug' `factor`

util/build-gnu.sh

@@ -70,19 +70,38 @@ sed -i 's|^"\$@|/usr/bin/timeout 600 "\$@|' build-aux/test-driver
 sed -i "s/^[[:blank:]]*PATH=.*/  PATH='${UU_BUILD_DIR//\//\\/}\$(PATH_SEPARATOR)'\"\$\$PATH\" \\\/" Makefile
 sed -i 's| tr | /usr/bin/tr |' tests/init.sh
 make -j "$(nproc)"
-# Generate the factor tests, so they can be fixed
-# Used to be 36. Reduced to 20 to decrease the log size
-for i in {00..20}; do
-    make "tests/factor/t${i}.sh"
-done
-
-# strip the long stuff
-for i in {21..36}; do
+first=00
+if test ${UU_MAKE_PROFILE} != "debug"; then
+    # Generate the factor tests, so they can be fixed
+    # * reduced to 20 to decrease log size (down from 36 expected by GNU)
+    # * only for 'release', skipped for 'debug' as redundant and too time consuming (causing timeout errors)
+    seq=$(
+        i=${first}
+        while test "$i" -le 20; do
+            printf '%02d ' $i
+            i=$(($i + 1))
+        done
+    )
+    for i in ${seq}; do
+        make "tests/factor/t${i}.sh"
+    done
+    sed -i -e 's|^seq |/usr/bin/seq |' -e 's|sha1sum |/usr/bin/sha1sum |' tests/factor/t*sh
+    first=21
+fi
+# strip all (debug) or just the longer (release) factor tests from Makefile
+seq=$(
+    i=${first}
+    while test "$i" -le 36; do
+        printf '%02d ' $i
+        i=$(($i + 1))
+    done
+)
+for i in ${seq}; do
+    echo "strip t${i}.sh from Makefile"
     sed -i -e "s/\$(tf)\/t${i}.sh//g" Makefile
 done
 
 grep -rl 'path_prepend_' tests/* | xargs sed -i 's| path_prepend_ ./src||'
-sed -i -e 's|^seq |/usr/bin/seq |' -e 's|sha1sum |/usr/bin/sha1sum |' tests/factor/t*sh
 
 # Remove tests checking for --version & --help
 # Not really interesting for us and logs are too big