net-proxy/squid: fix build for GCC 14 (partially); use config cache for libltdl

* Fix build for GCC 14 (missing <algorithm> include for std::find, not upstreamed
  it yet). There's another issue I still need to look at to do with class visibility.

* Use config cache for libltdl which avoids some redundant configure checks.

Closes: https://bugs.gentoo.org/917161
Signed-off-by: Sam James <sam@gentoo.org>

net-proxy/squid/files/squid-6.4-gcc14-algorithm.patch

@@ -0,0 +1,12 @@
+https://bugs.gentoo.org/917161
+--- a/src/helper/Reply.cc
++++ b/src/helper/Reply.cc
+@@ -17,6 +17,8 @@
+ #include "rfc1738.h"
+ #include "SquidString.h"
+ 
++#include <algorithm>
++
+ Helper::Reply::Reply() :
+     result(Helper::Unknown)
+ {

net-proxy/squid/squid-6.4.ebuild

@@ -77,6 +77,7 @@ BDEPEND="
 PATCHES=(
 	"${FILESDIR}"/${PN}-6.2-gentoo.patch
 	"${FILESDIR}"/${PN}-4.17-use-system-libltdl.patch
+	"${FILESDIR}"/${PN}-6.4-gcc14-algorithm.patch
 )
 
 pkg_pretend() {
@@ -124,6 +125,8 @@ src_prepare() {
 
 src_configure() {
 	local myeconfargs=(
+		--cache-file="${S}"/config.cache
+
 		--datadir=/usr/share/squid
 		--libexecdir=/usr/libexec/squid
 		--localstatedir=/var