Support for FastRPC shell and dynamically loaded remote interfaces

[flamingradian]

This adds support for using the FastRPC shell and an apps_mem remote method for allocating memory.

Demo hexagon_nn client:

#include <inttypes.h>
#include <stdio.h>
#include <string.h>

#include <libhexagonrpc/fastrpc.h>
#include <libhexagonrpc/interfaces/remotectl.def>
#include <libhexagonrpc/session.h>

int main()
{
	const char *name = "hexagon_nn";
	uint32_t handle, dlerr;
	char err[256];
	int ret, fd;

	fd = hexagonrpc_fd_from_env();
	if (fd == -1)
		return 1;

	ret = fastrpc2(&remotectl_open_def, fd, REMOTECTL_HANDLE,
		       strlen(name) + 1, name,
		       &handle, &dlerr,
		       256, err);
	if (ret == -1) {
		perror("Could not open hexagon_nn");
		return 1;
	} else if (ret) {
		fprintf(stderr, "Could not open hexagon_nn: %d\n", ret);
		return 1;
	}

	if (dlerr) {
		fprintf(stderr, "Could not open hexagon_nn: %s\n", err);
		return 1;
	}

	printf("Got hexagon_nn handle: %" PRIx32 "\n", handle);

	fastrpc2(&remotectl_close_def, fd, REMOTECTL_HANDLE,
		 handle, &dlerr, 0, NULL);

	return 0;
}

Demo:

$ sudo -u fastrpc build/hexagonrpcd/hexagonrpcd \
	-f /dev/fastrpc-cdsp -d cdsp \
	-c /usr/share/qcom/sdm670/Google/sargo/dsp/cdsp/fastrpc_shell_3 \
	-R /usr/share/qcom/sdm670/Google/sargo/ -p sh