configure.ac: add AC_PROG_CPP

Otherwise, the preprocessor is not detected and it leads to failure with
empty $CPP variable being used on la_TYPE_UID_T, leading to a cascade of
detection errors and redefinition of some types.

diff --git a/configure.ac b/configure.ac
index 3b4602f5eebcd04ca5420b8c37e7a4dbac4fbedc..d51fa19cc9b284ae0f0e97d458f4c176a2b1f3b3 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -107,6 +107,7 @@ AC_SUBST(PLATFORMCPPFLAGS)
 AC_PROG_CC
 AC_PROG_CC_C99
 AM_PROG_CC_C_O
+AC_PROG_CPP
 AC_USE_SYSTEM_EXTENSIONS
 AC_LIBTOOL_WIN32_DLL
 AC_PROG_LIBTOOL