igt/gem_ctx_param: Tidy error messages

Avoid macro expansion inside the asserts so that the error messages are
readable.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/lib/ioctl_wrappers.c b/lib/ioctl_wrappers.c
index 110465e..8632878 100644
--- a/lib/ioctl_wrappers.c
+++ b/lib/ioctl_wrappers.c
@@ -871,6 +871,17 @@
 	do_ioctl(fd, DRM_IOCTL_I915_GEM_CONTEXT_DESTROY, &destroy);
 }
 
+int __gem_context_get_param(int fd, struct local_i915_gem_context_param *p)
+{
+#define LOCAL_I915_GEM_CONTEXT_GETPARAM       0x34
+#define LOCAL_IOCTL_I915_GEM_CONTEXT_GETPARAM DRM_IOWR (DRM_COMMAND_BASE + LOCAL_I915_GEM_CONTEXT_GETPARAM, struct local_i915_gem_context_param)
+	if (igt_ioctl(fd, LOCAL_IOCTL_I915_GEM_CONTEXT_GETPARAM, p))
+		return -errno;
+
+	errno = 0;
+	return 0;
+}
+
 /**
  * gem_context_get_param:
  * @fd: open i915 drm file descriptor
@@ -883,11 +894,10 @@
  */
 void gem_context_get_param(int fd, struct local_i915_gem_context_param *p)
 {
-#define LOCAL_I915_GEM_CONTEXT_GETPARAM       0x34
-#define LOCAL_IOCTL_I915_GEM_CONTEXT_GETPARAM DRM_IOWR (DRM_COMMAND_BASE + LOCAL_I915_GEM_CONTEXT_GETPARAM, struct local_i915_gem_context_param)
-	do_ioctl(fd, LOCAL_IOCTL_I915_GEM_CONTEXT_GETPARAM, p);
+	igt_assert(__gem_context_get_param(fd, p) == 0);
 }
 
+
 int __gem_context_set_param(int fd, struct local_i915_gem_context_param *p)
 {
 #define LOCAL_I915_GEM_CONTEXT_SETPARAM       0x35
diff --git a/lib/ioctl_wrappers.h b/lib/ioctl_wrappers.h
index 0d42ba9..115011c 100644
--- a/lib/ioctl_wrappers.h
+++ b/lib/ioctl_wrappers.h
@@ -126,6 +126,7 @@
 void gem_context_get_param(int fd, struct local_i915_gem_context_param *p);
 void gem_context_set_param(int fd, struct local_i915_gem_context_param *p);
 int __gem_context_set_param(int fd, struct local_i915_gem_context_param *p);
+int __gem_context_get_param(int fd, struct local_i915_gem_context_param *p);
 
 #define LOCAL_I915_GEM_USERPTR       0x33
 #define LOCAL_IOCTL_I915_GEM_USERPTR DRM_IOWR (DRM_COMMAND_BASE + LOCAL_I915_GEM_USERPTR, struct local_i915_gem_userptr)