Windows: Use the Windows style PATH separator ';'.

Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>
diff --git a/Documentation/git.txt b/Documentation/git.txt
index 7414238..4e4bd6d 100644
--- a/Documentation/git.txt
+++ b/Documentation/git.txt
@@ -409,9 +409,9 @@
 'GIT_ALTERNATE_OBJECT_DIRECTORIES'::
 	Due to the immutable nature of git objects, old objects can be
 	archived into shared, read-only directories. This variable
-	specifies a ":" separated list of git object directories which
-	can be used to search for git objects. New objects will not be
-	written to these directories.
+	specifies a ":" separated (on Windows ";" separated) list
+	of git object directories which can be used to search for git
+	objects. New objects will not be written to these directories.
 
 'GIT_DIR'::
 	If the 'GIT_DIR' environment variable is set then it
diff --git a/compat/mingw.h b/compat/mingw.h
index e5c0c6b..22aae00 100644
--- a/compat/mingw.h
+++ b/compat/mingw.h
@@ -132,3 +132,9 @@
 struct passwd *getpwuid(int uid);
 int setitimer(int type, struct itimerval *in, struct itimerval *out);
 int sigaction(int sig, struct sigaction *in, struct sigaction *out);
+
+/*
+ * git specific compatibility
+ */
+
+#define PATH_SEP ';'
diff --git a/exec_cmd.c b/exec_cmd.c
index e189cac..a1bc4e0 100644
--- a/exec_cmd.c
+++ b/exec_cmd.c
@@ -37,7 +37,7 @@
 		else
 			strbuf_addstr(out, make_absolute_path(path));
 
-		strbuf_addch(out, ':');
+		strbuf_addch(out, PATH_SEP);
 	}
 }
 
diff --git a/git-compat-util.h b/git-compat-util.h
index da7249a..9dc733e 100644
--- a/git-compat-util.h
+++ b/git-compat-util.h
@@ -110,6 +110,10 @@
 #define PRIuMAX "llu"
 #endif
 
+#ifndef PATH_SEP
+#define PATH_SEP ':'
+#endif
+
 #ifdef __GNUC__
 #define NORETURN __attribute__((__noreturn__))
 #else
diff --git a/sha1_file.c b/sha1_file.c
index 191f814..6f004ff 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -392,7 +392,7 @@
 	if (!alt) alt = "";
 
 	alt_odb_tail = &alt_odb_list;
-	link_alt_odb_entries(alt, alt + strlen(alt), ':', NULL, 0);
+	link_alt_odb_entries(alt, alt + strlen(alt), PATH_SEP, NULL, 0);
 
 	read_info_alternates(get_object_directory(), 0);
 }