update: fix hashing of text files with empty lines

the current status file for 1.1.9 is one of these
(cherry picked from commit b3c26d999de3d0d56edf93e32ff448725010a1ff)
Signed-off-by: Rafaël Carré <rafael.carre@gmail.com>

src/misc/update_crypto.c

@@ -730,15 +730,18 @@ uint8_t *hash_sha1_from_text( const char *psz_string,
     while( *psz_string )
     {
         size_t i_len = strcspn( psz_string, "\r\n" );
-        if( !i_len )
-            break;
 
-        gcry_md_write( hd, psz_string, i_len );
+        if( i_len )
+        {
+            gcry_md_write( hd, psz_string, i_len );
+            psz_string += i_len;
+        }
         gcry_md_putc( hd, '\r' );
         gcry_md_putc( hd, '\n' );
 
-        psz_string += i_len;
-        while( *psz_string == '\r' || *psz_string == '\n' )
+        if( *psz_string == '\r' )
+            psz_string++;
+        if( *psz_string == '\n' )
             psz_string++;
     }
     else