Replace strdup function by osl_util_strdup function or OSL_strdup macro
strdup function is not standardized
Fix the warning: "implicit declaration of function 'strdup'"
Fix warning: comparison between signed and unsigned integer expressions
Replace mkstemp function (POSIX) by tmpfile function (standard) in osl_test.c and fix warnings
Add a fake member in osl_null structure to disable warning
Merge pull request #8 from Lnc/fix_warning

Fix warnings