fix formatting for (non-generated) internal source files

- Change formatting standard to Cpp11. Main difference is not having
  the space between two closing >> for nested templates. We don't
  choose c++14, because older versions of clang-format (version 9
  and earlier) don't know this value yet, and it doesn't make a
  difference in the formatting.
- Apply clang-format to all (non generated) internal source files.
- Manually fix some code sections (clang-format on/off) and c-strings
- Exclude some embedded external files with very different formatting
  (gtest/gmock)
- Add script to format all source files

Change-Id: Ic6cea41575ad6e37c9e136dbce176b0d505dc44d

internal/ceres/stringprintf.h

@@ -55,9 +55,9 @@ namespace internal {
 // have an implicit 'this' argument, the arguments of such methods
 // should be counted from two, not one."
 #define CERES_PRINTF_ATTRIBUTE(string_index, first_to_check) \
-    __attribute__((__format__ (__printf__, string_index, first_to_check)))
+  __attribute__((__format__(__printf__, string_index, first_to_check)))
 #define CERES_SCANF_ATTRIBUTE(string_index, first_to_check) \
-    __attribute__((__format__ (__scanf__, string_index, first_to_check)))
+  __attribute__((__format__(__scanf__, string_index, first_to_check)))
 #else
 #define CERES_PRINTF_ATTRIBUTE(string_index, first_to_check)
 #endif
@@ -68,7 +68,9 @@ extern std::string StringPrintf(const char* format, ...)
     CERES_PRINTF_ATTRIBUTE(1, 2);
 
 // Store result into a supplied string and return it.
-extern const std::string& SStringPrintf(std::string* dst, const char* format, ...)
+extern const std::string& SStringPrintf(std::string* dst,
+                                        const char* format,
+                                        ...)
     // Tell the compiler to do printf format string checking.
     CERES_PRINTF_ATTRIBUTE(2, 3);