Fix issues identified by static analyzer in BasicRandom.c and ExtendedRandom.c

[ibmkramamoo]

BasicRandom.c:
Input parameters such as bytes and seed are not validated for NULL. line 41, line 85
line 133: ICC_GenerateRandomSeed(ockCtx, &status, size, seedNative); - return value must be checked. if (status.majRC != ICC_OK)

ExtendedRandom.c: line 41: algName is not checked for being NULL.
Line 179: seed is not being checked for being NULL.

[ibmkramamoo]

Static analyzer recommends common cleanup and return instead of nested ifs.