gnu: inputattach: Build with -O2.

* gnu/packages/linux.scm (inputattach)[arguments]: Pass "-O2" to GCC.

gnu/packages/linux.scm

@@ -5213,7 +5213,7 @@ (define-public inputattach
              (with-directory-excursion "inputattach"
                (invoke (string-append (assoc-ref inputs "gcc")
                                       "/bin/gcc")
-                       "-o" "inputattach" "inputattach.c"))
+                       "-O2" "-o" "inputattach" "inputattach.c"))
              #t))
          (delete 'check)
          (replace 'install