bitvec: Add get/set byte sequences

The new functions bitvec_get_bytes and bitvec_set_bytes copy
byte sequences from bitvecs to uint8_t arrays and vice versa.
While the bytes in the bitvecs do not need to be aligned, the uint8_t
arrays always are. In case the bytes in the bitvec are aligned, the
implementation uses memcpy.

Note that the implementation like the other existing functions assume
MSB first encoding.

[hfreyther: Squash the comment fix into this commit as well]

Sponsored-by: On-Waves ehf
diff --git a/tests/testsuite.at b/tests/testsuite.at
index 85c3e8b..55e79f1 100644
--- a/tests/testsuite.at
+++ b/tests/testsuite.at
@@ -21,6 +21,12 @@
 AT_CHECK([$abs_top_builddir/tests/bits/bitrev_test], [0], [expout])
 AT_CLEANUP
 
+AT_SETUP([bitvec])
+AT_KEYWORDS([bitvec])
+cat $abs_srcdir/bitvec/bitvec_test.ok > expout
+AT_CHECK([$abs_top_builddir/tests/bitvec/bitvec_test], [0], [expout], [ignore])
+AT_CLEANUP
+
 AT_SETUP([conv])
 AT_KEYWORDS([conv])
 cat $abs_srcdir/conv/conv_test.ok > expout