Add comments about raw random integer functions & garbage collection

[ci skip]

Author: d-torrance

M2/Macaulay2/e/interface/random.h

@@ -27,9 +27,11 @@ int32_t rawRandomInt(int32_t max);
 
 void rawSetRandomInteger(mpz_ptr result, gmp_ZZ maxN);
 /* if height is the null pointer, use the default height */
+/* doesn't deal w/ garbage collection */
 
 gmp_ZZ rawRandomInteger(gmp_ZZ maxN);
 /* if height is the null pointer, use the default height */
+/* returns garbage-collected memory */
 
 void rawSetFareyApproximation(mpq_ptr result, gmp_RR x, gmp_ZZ height);
 /* sets result = the nearest rational to x w/ denominator <= height */