Fix linux compilation

Author: tstenner

build_mex.m

@@ -3,14 +3,14 @@
 % You also need the liblsl64 binary in the bin folder and a configured
 % C compiler (mex -setup)
 
-libs = '-llsl64';
+libs = {'-llsl64'};
 if ispc
 	dllext = 'dll';
 elseif ismac
 	dllext = 'dylib';
 elseif isunix
 	dllext = 'so';
-	libs = ['-llsl64 -ldl'];
+	libs = {'-llsl64','-ldl'};
 end
 
 
@@ -27,7 +27,7 @@
 	[~, base, ~] = fileparts(f.name);
 	targetstats = dir([base, ext]);
 	if isempty(targetstats) || f.datenum > targetstats.datenum
-		mex('-I../../liblsl/include','-L.', libs, ['../mex/', f.name]);
+		mex('-I../../liblsl/include','-L.', libs{:}, ['../mex/', f.name]);
 	else
 		disp([base, ext, ' up to date']);
 	end

mex/lsl_loadlib_.c

@@ -118,7 +118,7 @@ void mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray*prhs[]) {
 	lsl_remove_child_t lsl_remove_child;
 
 	/* the same as list of strings... */
-	char *fieldnames[] = {"hlib","lsl_protocol_version", "lsl_library_version", "lsl_local_clock", "lsl_resolve_all", "lsl_resolve_byprop", "lsl_resolve_bypred", "lsl_create_streaminfo", "lsl_destroy_streaminfo", 
+	const char *fieldnames[] = {"hlib","lsl_protocol_version", "lsl_library_version", "lsl_local_clock", "lsl_resolve_all", "lsl_resolve_byprop", "lsl_resolve_bypred", "lsl_create_streaminfo", "lsl_destroy_streaminfo", 
 		"lsl_get_name", "lsl_get_type", "lsl_get_channel_count", "lsl_get_nominal_srate", "lsl_get_channel_format", "lsl_get_source_id", "lsl_get_version", "lsl_get_created_at",
 		"lsl_get_uid", "lsl_get_session_id", "lsl_get_hostname", "lsl_get_desc", "lsl_get_xml", "lsl_create_outlet", "lsl_destroy_outlet", "lsl_push_sample_f", "lsl_push_sample_ft", "lsl_push_sample_ftp", 
         "lsl_push_sample_d", "lsl_push_sample_dt" , "lsl_push_sample_dtp", "lsl_push_sample_l", "lsl_push_sample_lt", "lsl_push_sample_ltp",  "lsl_push_sample_i", "lsl_push_sample_it",