pathspec: support :(glob) syntax

:(glob)path differs from plain pathspec that it uses wildmatch with
WM_PATHNAME while the other uses fnmatch without FNM_PATHNAME. The
difference lies in how '*' (and '**') is processed.

With the introduction of :(glob) and :(literal) and their global
options --[no]glob-pathspecs, the user can:

 - make everything literal by default via --noglob-pathspecs
   --literal-pathspecs cannot be used for this purpose as it
   disables _all_ pathspec magic.

 - individually turn on globbing with :(glob)

 - make everything globbing by default via --glob-pathspecs

 - individually turn off globbing with :(literal)

The implication behind this is, there is no way to gain the default
matching behavior (i.e. fnmatch without FNM_PATHNAME). You either get
new globbing or literal. The old fnmatch behavior is considered
deprecated and discouraged to use.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

pathspec.h

@@ -5,10 +5,12 @@
 #define PATHSPEC_FROMTOP	(1<<0)
 #define PATHSPEC_MAXDEPTH	(1<<1)
 #define PATHSPEC_LITERAL	(1<<2)
+#define PATHSPEC_GLOB		(1<<3)
 #define PATHSPEC_ALL_MAGIC	  \
 	(PATHSPEC_FROMTOP	| \
 	 PATHSPEC_MAXDEPTH	| \
-	 PATHSPEC_LITERAL)
+	 PATHSPEC_LITERAL	| \
+	 PATHSPEC_GLOB)
 
 #define PATHSPEC_ONESTAR 1	/* the pathspec pattern sastisfies GFNM_ONESTAR */