As a slight hack, reference glXWaitGL to pull in libGL in the right order

* Basically we want libGL to be loaded second, after librenderdoc. This is
  in order to make sure dlsym(RTLD_NEXT) can work.
* This can be done just by order in the ld command. Unfortunately since
  renderdoccmd links directly against librenderdoc (rather than LD_PRELOAD)
  any symbols exported by librenderdoc resolve, so unless we reference a
  function that isn't exported by librenderdoc, libGL won't be linked in
  at all.
* I realise this is probably a horrible hack, but it works for now.

renderdoccmd/Makefile

@@ -5,9 +5,9 @@ MACROS=-DLINUX \
 			 -DRENDERDOC_EXPORTS \
 			 -DGIT_COMMIT_HASH='"'$$(git rev-parse HEAD)'"' \
 			 -DRENDERDOC_VERSION_STRING='"0.20"'
-CFLAGS=-c -Wall -Werror -fPIC $(MACROS) -I.
+CFLAGS=-c -Wall -Werror -fPIC $(MACROS) -I../renderdoc/
 CPPFLAGS=-std=c++11 -g -Wno-unused -Wno-unknown-pragmas -Wno-reorder
-LDFLAGS=-L../renderdoc -lrenderdoc
+LDFLAGS=-L../renderdoc -lrenderdoc -lGL
 OBJECTS=linux_specific.o
 
 all: bin/renderdoccmd

renderdoccmd/linux_specific.cpp

@@ -23,9 +23,19 @@
  ******************************************************************************/
 
 #include <stdio.h>
+#include <replay/renderdoc.h>
+
+// symbol defined in libGL but not librenderdoc.
+// Forces link of libGL after renderdoc (otherwise all symbols would
+// be resolved and libGL wouldn't link, meaning dlsym(RTLD_NEXT) would fai
+extern "C" void glXWaitGL();
 
 int main()
 {
-	puts("foo");
+	RENDERDOC_SpawnReplayHost(NULL);
+
+	volatile bool never_run = false;
+	if(never_run) glXWaitGL();
+
 	return 0;
 }