package/libglvnd: needs dynamic library

libglvnd needs dynamic library since the addition of the package in
commit 0378e2e5d9ce9d5676975dfbff501360094fdc1a:

/libglvnd_pthread.a.p/glvnd_pthread.c.o -c ../src/util/glvnd_pthread.c
../src/util/glvnd_pthread.c:33:10: fatal error: dlfcn.h: No such file or directory
   33 | #include <dlfcn.h>
      |          ^~~~~~~~~

Fixes:
 - http://autobuild.buildroot.org/results/c5e92f0b355c91cdcebe0070499889473996f337

Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Yann E. MORIN <yann.morin.1998@free.fr>

package/libglvnd/Config.in

@@ -1,5 +1,6 @@
 config BR2_PACKAGE_LIBGLVND
 	bool "libglvnd"
+	depends on !BR2_STATIC_LIBS # dlfcn.h
 	help
 	  The GL Vendor-Neutral Dispatch library
 
@@ -42,3 +43,6 @@ config BR2_PACKAGE_PROVIDES_LIBGLES
 	default "libglvnd" if BR2_PACKAGE_LIBGLVND_DISPATCH_GLES
 
 endif
+
+comment "libglvnd needs a toolchain w/ dynamic library"
+	depends on BR2_STATIC_LIBS