Handle infinite floating point values correctly in C code generator.
Handle infinite floating point values correctly in C code generator.

mrakgr/futhark,HIPERFIT/futhark,diku-dk/futhark,diku-dk/futhark,HIPERFIT/futhark,ihc/futhark,diku-dk/futhark,mrakgr/futhark,ihc/futhark,ihc/futhark,diku-dk/futhark,diku-dk/futhark,HIPERFIT/futhark,mrakgr/futhark