Gentoo uses non-standard naming for slotted iniparser:4 and it
does not have a pkg-config file (ideally should be unslotted).
Cava can use iniparser:0 as well but <3.2 forces legacy mode.
--- a/configure.ac
+++ b/configure.ac
@@ -259,6 +259,6 @@
 
-AC_CHECK_LIB(iniparser,iniparser_load, have_iniparser=yes, have_iniparser=no)
+AC_CHECK_LIB(iniparser4,iniparser_load, have_iniparser=yes, have_iniparser=no)
     if [[ $have_iniparser = "yes" ]] ; then
-    LIBS="$LIBS -liniparser"
-      CPPFLAGS="$CPPFLAGS -I/usr/include/iniparser"
+    LIBS="$LIBS -liniparser4"
+      CPPFLAGS="$CPPFLAGS -I${GENTOO_SYSROOT}/usr/include/iniparser4"
     AC_LINK_IFELSE([AC_LANG_PROGRAM([[#include <iniparser.h>]],