MinGW: Convert CR/LF to LF in tag signatures

On Windows, gpg outputs CR/LF signatures.  But since the tag
messages are already stripped of the CR by stripspace(), it is
arguably nicer to do the same for the tag signature.  Actually,
this patch does not look for CR/LF, but strips all CRs
from the signature.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

builtin-tag.c

@@ -229,6 +229,20 @@ static ssize_t do_sign(char *buffer, size_t size, size_t max)
 	if (len == max - size)
 		return error("could not read the entire signature from gpg.");
 
+#ifdef __MINGW32__
+	/* strip CR from the line endings */
+	{
+		int i, j;
+		for (i = j = 0; i < len; i++)
+			if (buffer[size + i] != '\r') {
+				if (i != j)
+					buffer[size + j] = buffer[size + i];
+				j++;
+			}
+		len = j;
+	}
+#endif
+
 	return size + len;
 }