Fix rendering of non-BMP characters at start or end of text run

We currently discover a non-BMP character at the start or end of a
text run only after we process both halves of the surrogate pair
representing the character individually, resulting in off-by-one errors
in calculating the portion of the char array containing the run to be
drawn (we erroneously omit any high surrogate at the start of a run, and
erroneously include any high surrogate immediately following the end of
a run).

Fix this by processing both halves of the surrogate pair immediately
when we see the high surrogate.

Author: steven676

libraries/emulatorview/src/jackpal/androidterm/emulatorview/TranscriptScreen.java

@@ -204,19 +204,16 @@ public final void drawText(int row, Canvas canvas, float x, float y,
         int lastRunStart = -1;
         int lastRunStartIndex = -1;
         boolean forceFlushRun = false;
-        char cHigh = 0;
         int column = 0;
         int index = 0;
         while (column < columns) {
-            int style;
+            int style = color.get(column);
             boolean cursorStyle = false;
-            style = color.get(column);
+            int incr = 1;
             int width;
             if (Character.isHighSurrogate(line[index])) {
-                cHigh = line[index++];
-                continue;
-            } else if (Character.isLowSurrogate(line[index])) {
-                width = UnicodeTranscript.charWidth(cHigh, line[index]);
+                width = UnicodeTranscript.charWidth(line, index);
+                incr++;
             } else {
                 width = UnicodeTranscript.charWidth(line[index]);
             }
@@ -242,7 +239,7 @@ public final void drawText(int row, Canvas canvas, float x, float y,
             }
             runWidth += width;
             column += width;
-            index++;
+            index += incr;
             if (width > 1) {
                 /* We cannot draw two or more East Asian wide characters in the
                    same run, because we need to make each wide character take