fix .parse-deps when input spans multiple lines

.parse-deps breaks when inputs such as the following are passed:

foo.o: \
  foo.c \
  foo.h

There's 3 issues:
1. The first \ wouldn't be folded as the space prior to the \ would be
   removed by the removal of the target name.
2. Extra spaces would end up in front of every name in the final output.
3. \n in the pattern of the s command is not portable to non-gnu-sed.

The new version's folding loop:
1. Removes any double forward slashes currently present in the pattern
   space.
2. Adds a double forward slash at the end of the line.
3. Removes the backslash, double forward slash, character following it
   (newline) and any spaces following that character.

This solves all three problems.

1 files changed, 4 insertions, 2 deletions

diff --git a/.parse-deps b/.parse-deps
index cad20d9..e8dc74b 100755
--- a/.parse-deps
+++ b/.parse-deps
@@ -4,12 +4,14 @@
 # collapse lines
 :loop
 /\\$/ {
+	s|///*|/|g
+	s|$|//|
 	N
-	s/ \\\n//
+	s|\\//. *||
 	b loop
 }
 # split on unescaped spaces
-s/\([^\]\) /\1\
+s/\([^\]\)  */\1\
 /g
 # unescape spaces
 s/\\ / /g