Add the ability to generate a C source file, which is in addition to the
existing functionality of generating binary.
An example of the generated source:
```c
#ifdef __APPLE__
#define FORMATTER_SECTION "__DATA_CONST,__lldbformatters"
#else
#define FORMATTER_SECTION ".lldbformatters"
#endif
__attribute__((used, section(FORMATTER_SECTION)))
unsigned char _Account_synthetic[] =
// version
"\x01"
// remaining record size
"\x15"
// type name size
"\x07"
// type name
"Account"
// flags
"\x00"
// sig_get_num_children
"\x02"
// program size
"\x02"
// program
"\x20\x01"
// sig_get_child_at_index
"\x04"
// program size
"\x06"
// program
"\x02\x20\x00\x23\x11\x60"
;
```
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