patch 9.1.1250: cannot set the maximum popup menu width

Problem:  cannot set the maximum popup menu width
          (Lucas Mior)
Solution: add the new global option value 'pummaxwidth'
          (glepnir)

fixes: #10901
closes: #16943

Signed-off-by: glepnir <glephunter@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/option.h b/src/option.h
index 5714e0c..0b568f1 100644
--- a/src/option.h
+++ b/src/option.h
@@ -545,6 +545,7 @@
 #endif
 EXTERN long	p_ph;		// 'pumheight'
 EXTERN long	p_pw;		// 'pumwidth'
+EXTERN long	p_pmw;		// 'pummaxwidth'
 EXTERN char_u	*p_com;		// 'comments'
 EXTERN char_u	*p_cpo;		// 'cpoptions'
 #ifdef FEAT_CSCOPE