Add -Wl,-no-as-needed to Linux Makefile.

GCC's linker drops dependency on libGL because neither MuJoCo, GLFW, nor the sample applications themselves explicitly depend on OpenGL symbols.

PiperOrigin-RevId: 439372170
Change-Id: I122d1d9658484e901f422d35395ad5929c7a9021

sample/Makefile

@@ -2,7 +2,7 @@
 # which is commonly available through your distro's package manager.
 # On Debian and Ubuntu, GLFW can be installed via `apt install libglfw3-dev`.
 
-COMMON=-O2 -I../include -L../lib -std=c++11 -pthread -Wl,-rpath,'$$ORIGIN'/../lib
+COMMON=-O2 -I../include -L../lib -std=c++11 -pthread -Wl,-no-as-needed -Wl,-rpath,'$$ORIGIN'/../lib
 
 all:
 	$(CXX) $(COMMON) testxml.cc    -lmujoco             -o ../bin/testxml