[flang] Handle leading zeroes after decimal in REAL formatted input

[klausler]

Summary

Leading zero digits after the decimal mark were being dropped.

flang/runtime/edit-input.cpp

for (; next; next = io.NextInField(remaining)) {
       char32_t ch{*next};
       if (ch == ' ' || ch == '\t') {
         if (edit.modes.editingFlags & blankZero) {
           ch = '0'; // BZ mode - treat blank as if it were zero
         } else {
           continue;
         }
       }
-      if (ch == '0' && got == start) {
-        // omit leading zeroes
+      if (ch == '0' && got == start && !decimalPoint) {
+        // omit leading zeroes before the decimal
       } else if (ch >= '0' && ch <= '9') {
         if (got < bufferSize) {
           buffer[got++] = ch;
         }
       } else if (ch == decimal && !decimalPoint) {
         // the decimal point is *not* copied to the buffer
         decimalPoint = got - start; // # of digits before the decimal point
       } else {

flang/unittests/Runtime/hello.cpp

int main() {
   realTest("(F5.3,';')", -0.025, "-.025;");
   realTest("(F5.3,';')", -0.0025, "-.003;");
   realTest("(F5.3,';')", -0.00025, "-.000;");
   realTest("(F5.3,';')", -0.000025, "-.000;");
 
   realInTest("(F18.0)", "                 0", 0x0);
   realInTest("(F18.0)", "                  ", 0x0);
   realInTest("(F18.0)", "                -0", 0x8000000000000000);
+  realInTest("(F18.0)", "                01", 0x3ff0000000000000);
   realInTest("(F18.0)", "                 1", 0x3ff0000000000000);
   realInTest("(F18.0)", "              125.", 0x405f400000000000);
   realInTest("(F18.0)", "              12.5", 0x4029000000000000);
   realInTest("(F18.0)", "              1.25", 0x3ff4000000000000);
+  realInTest("(F18.0)", "             01.25", 0x3ff4000000000000);
   realInTest("(F18.0)", "              .125", 0x3fc0000000000000);
+  realInTest("(F18.0)", "             0.125", 0x3fc0000000000000);
+  realInTest("(F18.0)", "             .0625", 0x3fb0000000000000);
+  realInTest("(F18.0)", "            0.0625", 0x3fb0000000000000);
   realInTest("(F18.0)", "               125", 0x405f400000000000);
   realInTest("(F18.1)", "               125", 0x4029000000000000);
   realInTest("(F18.2)", "               125", 0x3ff4000000000000);
   realInTest("(F18.3)", "               125", 0x3fc0000000000000);
   realInTest("(-1P,F18.0)", "               125", 0x4093880000000000); // 1250
   realInTest("(1P,F18.0)", "               125", 0x4029000000000000); // 12.5
   realInTest("(BZ,F18.0)", "              125 ", 0x4093880000000000); // 1250
   realInTest("(DC,F18.0)", "              12,5", 0x4029000000000000);
 
   return EndTests();
 }