package/waf: purge trailing '/' from WAF_SITE

<PKG>_SITE cannot have a trailing slash.

This was not detected by the check in generic-package because it is a
host-only package without Config.in symbol.

Signed-off-by: Carlos Santos <casantos@datacom.com.br>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>

package/waf/waf.mk

@@ -6,7 +6,7 @@
 
 WAF_VERSION = 1.9.5
 WAF_SOURCE = waf-$(WAF_VERSION)
-WAF_SITE = https://waf.io/
+WAF_SITE = https://waf.io
 
 define HOST_WAF_EXTRACT_CMDS
 	$(INSTALL) -D -m 0755 $(HOST_WAF_DL_DIR)/waf-$(WAF_VERSION) $(@D)/waf