dev-libs/libxslt: add USE=debugger

Before version 1.1.43 libxslt were built with debugger functionality
enabled by default, but since it's barely being used nowadays, it was
disabled in upstream. However there is still some legacy software in
overlays the depends upon it.

See-also: https://gitlab.gnome.org/GNOME/libxslt/-/commit/09b41917dd6fa12f7ca46462622c91bb72343196
Closes: https://bugs.gentoo.org/955057
Signed-off-by: Alexander Golubev <fatzer2@gmail.com>
Part-of: https://github.com/gentoo/gentoo/pull/43198
Closes: https://github.com/gentoo/gentoo/pull/43198
Signed-off-by: Sam James <sam@gentoo.org>

dev-libs/libxslt/libxslt-1.1.43-r1.ebuild

@@ -20,7 +20,7 @@ fi
 
 LICENSE="MIT"
 SLOT="0"
-IUSE="crypt debug examples python static-libs"
+IUSE="crypt debug debugger examples python static-libs"
 REQUIRED_USE="python? ( ${PYTHON_REQUIRED_USE} )"
 
 BDEPEND=">=virtual/pkgconfig-1"
@@ -59,6 +59,7 @@ multilib_src_configure() {
 			--without-python \
 			$(use_with crypt crypto) \
 			$(use_with debug) \
+			$(use_with debugger) \
 			$(use_enable static-libs static) \
 			"$@"
 	}

dev-libs/libxslt/libxslt-9999.ebuild

@@ -20,7 +20,7 @@ fi
 
 LICENSE="MIT"
 SLOT="0"
-IUSE="crypt debug examples python static-libs"
+IUSE="crypt debug debugger examples python static-libs"
 REQUIRED_USE="python? ( ${PYTHON_REQUIRED_USE} )"
 
 BDEPEND=">=virtual/pkgconfig-1"
@@ -59,6 +59,7 @@ multilib_src_configure() {
 			--without-python \
 			$(use_with crypt crypto) \
 			$(use_with debug) \
+			$(use_with debugger) \
 			$(use_enable static-libs static) \
 			"$@"
 	}

dev-libs/libxslt/metadata.xml

@@ -13,4 +13,7 @@
     <remote-id type="cpe">cpe:/a:xmlsoft:libxslt</remote-id>
     <remote-id type="gnome-gitlab">GNOME/libxslt</remote-id>
   </upstream>
+  <use>
+    <flag name="debugger">Build into the library callbacks and associated API for debugging XML processing.</flag>
+  </use>
 </pkgmetadata>