fix(cublas): prevent double-print in lookup_pkg awk END block

awk exit in the blank-line block jumps to END, which printed the
result again causing repo_sha to contain the hash twice with a newline,
breaking the sha256 string comparison.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

iso/builder/build-cublas.sh

@@ -50,12 +50,13 @@ lookup_pkg() {
         /^$/ {
             if (cur_pkg == pkg && cur_ver == ver) {
                 print cur_file " " cur_sha
+                printed=1
                 exit
             }
             cur_pkg=""; cur_ver=""; cur_file=""; cur_sha=""
         }
         END {
-            if (cur_pkg == pkg && cur_ver == ver) {
+            if (!printed && cur_pkg == pkg && cur_ver == ver) {
                 print cur_file " " cur_sha
             }
         }'