Enable Optimization (-O)

Note: For PowerLinux platforms only - when developing stub code for C programs, you cannot use this option in conjunction with either the -d symb flag or the -U flag. To work around the issue, either compile without the -O flag, or link to the shared object or library containing the code that is referenced.
Enables maximum performance at run time by carrying out the minimum run-time checks. This option is for use after all debugging has taken place and maximum performance with minimum run-time checks is required. The exact operation of this flag is environment dependent, but at a minimum it passes the NOCHECK directive to the Compiler. If any .c or .C files are being processed, this flag also is passed through to cc or the C++ compiler.