ls: Ensure file names are separated by 2 spaces

We need two spaces between filenames because that is the convention
followed by other implementations. More importantly, if we do not have
two spaces, certain Unicode file names cause filenames to run together.
In Unicode, combining characters come before the character they modify.
If a filename ends in a combining character, the combining character
attaches to the space that follows it, causing the space not to be
visible. Having a two-space gap stops the above issue from happening.

For context and a bit more information, see mailing list link below.
https://www.mail-archive.com/toybox@lists.landley.net/msg05986.html

toys/posix/ls.c

diff --git a/toys/posix/ls.c b/toys/posix/ls.c
index 0956902..d4c0211 100644
--- a/toys/posix/ls.c
+++ b/toys/posix/ls.c
@@ -384,7 +384,8 @@
       memset(colsizes, 0, columns*sizeof(unsigned));
       for (ul=0; ul<dtlen; ul++) {
         entrylen(sort[next_column(ul, dtlen, columns, &c)], len);
-        *len += totpad+1;
+        // Add `2` to `totpad` to ensure two spaces between filenames
+        *len += totpad+2;
         if (c == columns) break;
         // Expand this column if necessary, break if that puts us over budget
         if (*len > colsizes[c]) {