msi/tests: Write-strings warnings fix

[Andrew Talbot]

Changelog:
    msi/tests: Write-strings warnings fix.

diff -urN a/dlls/msi/tests/db.c b/dlls/msi/tests/db.c
--- a/dlls/msi/tests/db.c	2006-07-25 17:20:24.000000000 +0100
+++ b/dlls/msi/tests/db.c	2006-07-25 18:13:48.000000000 +0100
@@ -990,7 +990,7 @@
 static void test_where(void)
 {
     MSIHANDLE hdb = 0, rec;
-    LPSTR query;
+    LPCSTR query;
     UINT r;
 
     hdb = create_db();