package/unscd: disable on riscv32

unscd unconditionally uses __NR_clock_gettime which will raise the
following build failure on riscv32:

nscd-0.54.c:339:14: error: '__NR_clock_gettime' undeclared (first use in this function); did you mean 'clock_gettime'?
  339 |  if (syscall(__NR_clock_gettime, CLOCK_MONOTONIC, &ts))
      |              ^~~~~~~~~~~~~~~~~~
      |              clock_gettime

Fixes:
 - http://autobuild.buildroot.org/results/eb77b18f268d8e59c407f757662117a33d3f9ee3

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
(cherry picked from commit 34173da168f300b58957abb53c8f5fcaf8d8e605)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/unscd/Config.in

@@ -1,5 +1,6 @@
 config BR2_PACKAGE_UNSCD
 	bool "unscd"
+	depends on !BR2_RISCV_32
 	depends on BR2_TOOLCHAIN_USES_GLIBC
 	help
 	  Micro Name Service Caching Daemon
@@ -22,4 +23,5 @@ config BR2_PACKAGE_UNSCD
 	  http://busybox.net/~vda/unscd
 
 comment "unscd needs a glibc toolchain"
+	depends on !BR2_RISCV_32
 	depends on !BR2_TOOLCHAIN_USES_GLIBC