Fix crash in 256-color setup parsing

Applications can control the 256-color mode and change the palette. This
was not much used until now, but our terminal is now advertising itself
as xterm-256color. Mutt noticed this, tried to use the escape sequence,
and crashed Terminal here.

src/apps/terminal/TermParse.cpp

@@ -1518,7 +1518,7 @@ TermParse::_ProcessOperatingSystemControls(uchar* params)
 				// colors can be in "idx1:name1;...;idxN:nameN;" sequence too!
 				uint32 count = 0;
 				char* p = strtok((char*)params, ";");
-				do {
+				while (p != NULL && count < kTermColorCount) {
 					indexes[count] = atoi(p);
 
 					if (!reset) {
@@ -1532,7 +1532,7 @@ TermParse::_ProcessOperatingSystemControls(uchar* params)
 						count++;
 
 					p = strtok(NULL, ";");
-				} while (p != NULL && count < kTermColorCount);
+				};
 
 				if (count > 0) {
 					if (!reset)