Don't use ifdef HAVE_FOO check in the public mdbtools headers.
Note this is a bit of a hack hardcoding the values (HAVE_GLIB && HAVE_ICONV)
used when building the Fedora packages.

This fixes the following compile error when building libgda-mdb:

cc ... -c gda-mdb-provider.c  -fPIC -DPIC -o .libs/gda-mdb-provider.o
In file included from gda-mdb.h:33,
                 from gda-mdb-provider.c:37:
/usr/include/mdbtools.h:38:10: fatal error: mdbfakeglib.h: No such file or directory
   38 | #include <mdbfakeglib.h>
      |          ^~~~~~~~~~~~~~~
compilation terminated.

diff -up mdbtools-0.9.3/include/mdbsql.h~ mdbtools-0.9.3/include/mdbsql.h
--- mdbtools-0.9.3/include/mdbsql.h~	2020-12-17 20:07:00.000000000 +0100
+++ mdbtools-0.9.3/include/mdbsql.h	2021-07-10 13:02:45.392122848 +0200
@@ -25,11 +25,7 @@
 
 #include <stdio.h>
 #include <string.h>
-#ifdef HAVE_GLIB
 #include <glib.h>
-#else
-#include <mdbfakeglib.h>
-#endif
 #include <mdbtools.h>
 
 typedef struct MdbSQL
diff -up mdbtools-0.9.3/include/mdbtools.h~ mdbtools-0.9.3/include/mdbtools.h
--- mdbtools-0.9.3/include/mdbtools.h~	2021-04-05 15:45:40.000000000 +0200
+++ mdbtools-0.9.3/include/mdbtools.h	2021-07-10 13:02:57.377174793 +0200
@@ -32,17 +32,9 @@
 #include <string.h>
 #include <locale.h>
 
-#ifdef HAVE_GLIB
 #include <glib.h>
-#else
-#include <mdbfakeglib.h>
-#endif
 
-#if defined(HAVE_ICONV)
 #include <iconv.h>
-#elif defined(HAVE_XLOCALE_H)
-#include <xlocale.h>
-#endif
 
 #ifdef _WIN32
 #include <io.h>