Silence some "may be uninitialized when used" warning

Clang was complaining about some variables possibly being uninitialized
when used. The warnings are bogus, but clang can't figure that out. This
silences the warnings.
Reviewed-by: NRichard Levitte <levitte@openssl.org>

test/bioprinttest.c

@@ -92,7 +92,7 @@ static void dofptest(int test, double val, char *width, int prec, int *fail)
     int i;
 
     for (i = 0; i < 5; i++) {
-        char *fspec;
+        char *fspec = NULL;
         switch (i) {
         case 0:
             fspec = "e";
@@ -143,8 +143,8 @@ int main(int argc, char **argv)
     int test = 0;
     int i;
     int fail = 0;
-    int prec;
-    char *width;
+    int prec = -1;
+    char *width = "";
     const double frac = 2.0/3.0;
     char buf[80];