porting AT_TEST_CPP_GUARD_H to Sun C 5.7

[Paul Eggert]

Continuing to work my way through Beebe's reports for Bison 2.1, I
installed this:

2006-02-06  Paul Eggert  <address@hidden>

        * tests/headers.at (AT_TEST_CPP_GUARD_H): Use #include <...> rather
        than #include "...", and compile with -I'.'.  The old method was
        not portable, according to Posix and the C standard, and it does
        not work with Sun C 5.7, where previous #line directives affect
        the working directory used in later #include "..." directives.

--- tests/headers.at    1 Feb 2006 08:40:45 -0000       1.12
+++ tests/headers.at    6 Feb 2006 23:43:12 -0000
@@ -57,17 +57,17 @@ AS_MKDIR_P([$dirname])
 
 AT_DATA_GRAMMAR([$1.y],
 [%{
-#include "$1.h"
+#include <$1.h>
 %}
 %%
 dummy:;
 %%
-#include "$1.h"
+#include <$1.h>
 ])
 
 AT_CHECK([bison --defines=$1.h --output=y.tab.c $1.y])
 
-AT_COMPILE([y.tab.o], [-c y.tab.c])
+AT_COMPILE([y.tab.o], [-I. -c y.tab.c])
 
 AT_CLEANUP
 ])