configure: Ensure that config.h can be safely included multiple times.

Use AH_TOP and AH_BOTTOM macros so that the standard include guard
mechanisms are emitted by autoheader into the generated config.h file.

diff --git a/configure.ac b/configure.ac
index 74dd661..73ce67d 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -30,6 +30,10 @@ m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
 # Checks for library functions.
 AC_HEADER_STDC
 
+AH_TOP([#ifndef GLSL_CONFIG_H
+#define GLSL_CONFIG_H])
+AH_BOTTOM([#endif /* GLSL_CONFIG_H */])
+
 PKG_CHECK_MODULES([talloc], [talloc >= 2.0])
 
 AC_ARG_ENABLE([debug],