gtk: Makefile.am: Fix another typo.
-rw-r--r-- 414 .gitignore
-rw-r--r-- 35147 COPYING
-rw-r--r-- 2820 HACKING
-rw-r--r-- 838 Makefile.am
-rw-r--r-- 2169 README
-rwxr-xr-x 1527 autogen.sh
drwxr-xr-x - cli
-rw-r--r-- 11725 configure.ac
drwxr-xr-x - contrib
drwxr-xr-x - doc
drwxr-xr-x - gtk
drwxr-xr-x - gui
drwxr-xr-x - libsigrok
drwxr-xr-x - libsigrokdecode