PNaCl and DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS

[jungshik]

In utils.h, DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS is set to 1 only for architectures known to work correctly (and it's unset for architectures known not to support). For unknown architectures, a compile time error is emitted with #error pragma.

PNaCl (portable native client) is taken to '#error' branch. This was discovered when compiling ICU 61 for Chromium (ICU 61 does have a version of double-conversion library).

#elif defined(__pnacl__) || defined(__native_client__)
#undef DOUBLE_CONVERSION_CORRECT_DOUBLE_OPERATIONS
#else // final #else
#error "Target ... not detected s supported by Double-Conversion
#endif 

Perhaps adding one more #elif branch for PNaCl (and NaCl) as above would work.

ICU bug : https://ssl.icu-project.org/trac/ticket/13750

[floitschG]

Could you please review (and maybe test) #69

Thanks.

[jungshik]

Sorry for missing your ping. Thank you for fixing it.