[Support][Chrono] Use explicit cast of text output of time values.

rL316419 exposed a platform specific issue where the type of the values
passed to llvm::format could be different to the format string.

Debian unstable for mips uses long long int for std::chrono:duration,
while x86_64 uses long int.

For mips, this resulted in the value being corrupted when rendered to a
string. Address this by explicitly casting the result of the duration_cast
to the type specified in the format string.

Reviewers: sammccall

Differential Revision: https://reviews.llvm.org/D39597

llvm-svn: 317523
diff --git a/llvm/lib/Support/Chrono.cpp b/llvm/lib/Support/Chrono.cpp
index a39b485..84f5aab 100644
--- a/llvm/lib/Support/Chrono.cpp
+++ b/llvm/lib/Support/Chrono.cpp
@@ -65,17 +65,17 @@
     if (Style[I] == '%' && Style.size() > I + 1) switch (Style[I + 1]) {
         case 'L':  // Milliseconds, from Ruby.
           FStream << llvm::format(
-              "%.3lu", duration_cast<milliseconds>(Fractional).count());
+              "%.3lu", (long)duration_cast<milliseconds>(Fractional).count());
           ++I;
           continue;
         case 'f':  // Microseconds, from Python.
           FStream << llvm::format(
-              "%.6lu", duration_cast<microseconds>(Fractional).count());
+              "%.6lu", (long)duration_cast<microseconds>(Fractional).count());
           ++I;
           continue;
         case 'N':  // Nanoseconds, from date(1).
           FStream << llvm::format(
-              "%.6lu", duration_cast<nanoseconds>(Fractional).count());
+              "%.6lu", (long)duration_cast<nanoseconds>(Fractional).count());
           ++I;
           continue;
         case '%':  // Consume %%, so %%f parses as (%%)f not %(%f)