build: disable epoll and inotify checking outside linux

While compat shims exist for systems outside linux to provide
both, these require extra linkage and we're currently not set
up for that, besides we have native kqueue impls where relevant
so it's probably best to just disable.

configure.ac

@@ -470,7 +470,6 @@ AC_HEADER_TIME
 AC_CHECK_HEADERS([ \
 execinfo.h \
 mcheck.h \
-sys/inotify.h \
 sys/signalfd.h \
 sys/types.h \
 sys/param.h \
@@ -480,7 +479,8 @@ sys/auxv.h \
 asm/hwcap.h \
 ])
 
-if test "x${have_solaris}" != "xyes" ; then
+if test "x${have_linux}" = "xyes" ; then
+    AC_CHECK_HEADERS([sys/inotify.h])
     AC_CHECK_HEADERS([sys/epoll.h])
 fi