tests/extmod: Add a test for framebuf module, tested by coverage build.

tests/extmod/framebuf1.py

+try:
+    import framebuf
+except ImportError:
+    print("SKIP")
+    import sys
+    sys.exit()
+
+w = 5
+h = 16
+buf = bytearray(w * h // 8)
+fbuf = framebuf.FrameBuffer1(buf, w, h, w)
+
+# fill
+fbuf.fill(1)
+print(buf)
+fbuf.fill(0)
+print(buf)
+
+# put pixel
+fbuf.pixel(0, 0, 1)
+fbuf.pixel(4, 0, 1)
+fbuf.pixel(0, 15, 1)
+fbuf.pixel(4, 15, 1)
+print(buf)
+
+# get pixel
+print(fbuf.pixel(0, 0), fbuf.pixel(1, 1))
+
+# scroll
+fbuf.fill(0)
+fbuf.pixel(2, 7, 1)
+fbuf.scroll(0, 1)
+print(buf)
+fbuf.scroll(0, -2)
+print(buf)

tests/extmod/framebuf1.py.exp

+bytearray(b'\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff')
+bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00')
+bytearray(b'\x01\x00\x00\x00\x01\x80\x00\x00\x00\x80')
+1 0
+bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x01\x00\x00')
+bytearray(b'\x00\x00@\x00\x00\x00\x00\x00\x00\x00')

unix/mpconfigport_coverage.h

@@ -35,3 +35,4 @@
 #undef MICROPY_VFS_FAT
 #define MICROPY_FSUSERMOUNT            (1)
 #define MICROPY_VFS_FAT                (1)
+#define MICROPY_PY_FRAMEBUF            (1)