Tidy: Don't use floating point variables as loop counter.

The clang-tidy "cert-flp30-c" checker pointed out two locations where
a floating point variable was used as a loop counter.  Because of the
limitations of floating point variables, it is considered bad practice
and non-portable to use them as loop counters.  These two instances
are trivial enough that it shouldn't be a problem, but its easy to
correct them to use an integer loop counter.

https://clang.llvm.org/extra/clang-tidy/checks/cert-flp30-c.html

mythtv/libs/libmythui/DisplayResScreen.cpp

@@ -139,10 +139,10 @@ int DisplayResScreen::FindBestMatch(const DisplayResVector& dsr,
             {
                 while (!end)
                 {
-                    for (double precision = 0.001;
-                         precision < 1.0;
-                         precision *= 10.0)
+                    double precisions1[] = {0.001, 0.01, 0.1};
+                    for (uint p = 0; p < sizeof(precisions1); p++)
                     {
+                        double precision = precisions1[p];
                         for (size_t j=0; j < rates.size(); ++j)
                         {
                             // Multiple of target_rate will do
@@ -158,10 +158,10 @@ int DisplayResScreen::FindBestMatch(const DisplayResVector& dsr,
                     }
                     // Can't find exact frame rate, so try rounding to the
                     // nearest integer, so 23.97Hz will work with 24Hz etc
-                    for (double precision = 0.01;
-                         precision < 2.0;
-                         precision *= 10.0)
+                    double precisions2[] = {0.01, 0.1, 1};
+                    for (uint p = 0; p < sizeof(precisions2); p++)
                     {
+                        double precision = precisions2[p];
                         double rounded = round(videorate);
                         for (size_t j=0; j < rates.size(); ++j)
                         {