Revert "display HTML in default browser using Windows' shell API"

Since 4804aab (help (Windows): Display HTML in default browser using
Windows' shell API, 2008-07-13), Git for Windows used to call
`ShellExecute()` to launch the default Windows handler for `.html`
files.

The idea was to avoid going through a shell script, for performance
reasons.

However, this change ignores the `help.browser` config setting. Together
with browsing help not being a performance-critical operation, let's
just revert that patch.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/help.c

@@ -379,17 +379,10 @@ static void get_html_page_path(struct strbuf *page_path, const char *page)
 	free(to_free);
 }
 
-/*
- * If open_html is not defined in a platform-specific way (see for
- * example compat/mingw.h), we use the script web--browse to display
- * HTML.
- */
-#ifndef open_html
 static void open_html(const char *path)
 {
 	execl_git_cmd("web--browse", "-c", "help.browser", path, (char *)NULL);
 }
-#endif
 
 static void show_html_page(const char *git_cmd)
 {

compat/mingw.c

@@ -1930,48 +1930,6 @@ int mingw_raise(int sig)
 	}
 }
 
-
-static const char *make_backslash_path(const char *path)
-{
-	static char buf[PATH_MAX + 1];
-	char *c;
-
-	if (strlcpy(buf, path, PATH_MAX) >= PATH_MAX)
-		die("Too long path: %.*s", 60, path);
-
-	for (c = buf; *c; c++) {
-		if (*c == '/')
-			*c = '\\';
-	}
-	return buf;
-}
-
-void mingw_open_html(const char *unixpath)
-{
-	const char *htmlpath = make_backslash_path(unixpath);
-	typedef HINSTANCE (WINAPI *T)(HWND, const char *,
-			const char *, const char *, const char *, INT);
-	T ShellExecute;
-	HMODULE shell32;
-	int r;
-
-	shell32 = LoadLibrary("shell32.dll");
-	if (!shell32)
-		die("cannot load shell32.dll");
-	ShellExecute = (T)GetProcAddress(shell32, "ShellExecuteA");
-	if (!ShellExecute)
-		die("cannot run browser");
-
-	printf("Launching default browser to display HTML ...\n");
-	r = HCAST(int, ShellExecute(NULL, "open", htmlpath,
-				NULL, "\\", SW_SHOWNORMAL));
-	FreeLibrary(shell32);
-	/* see the MSDN documentation referring to the result codes here */
-	if (r <= 32) {
-		die("failed to launch browser for %.*s", MAX_PATH, unixpath);
-	}
-}
-
 int link(const char *oldpath, const char *newpath)
 {
 	typedef BOOL (WINAPI *T)(LPCWSTR, LPCWSTR, LPSECURITY_ATTRIBUTES);

compat/mingw.h

@@ -414,9 +414,6 @@ int mingw_offset_1st_component(const char *path);
 #include <inttypes.h>
 #endif
 
-void mingw_open_html(const char *path);
-#define open_html mingw_open_html
-
 /**
  * Converts UTF-8 encoded string to UTF-16LE.
  *