dev-libs/beecrypt: Override JNI CFLAG detection with eclass helper

The detection was failing for some people. I wasn't able to reproduce
this but the detection is a bit convoluted in any case so using the
eclass helper is much safer.

Closes: https://bugs.gentoo.org/582052
Package-Manager: Portage-2.3.24, Repoman-2.3.6

dev-libs/beecrypt/beecrypt-4.2.1-r4.ebuild

@@ -43,7 +43,7 @@ PATCHES=(
 
 pkg_setup() {
 	use python && python-single-r1_pkg_setup
-	use java && java-pkg-opt-2_pkg_setup
+	java-pkg-opt-2_pkg_setup
 }
 
 src_prepare() {
@@ -57,6 +57,7 @@ src_configure() {
 	append-cxxflags -std=c++14
 
 	# cplusplus needs threads support
+	ac_cv_java_include=$(use java && java-pkg_get-jni-cflags) \
 	econf \
 		--disable-expert-mode \
 		$(use_enable static-libs static) \