Fix memory leak when load_from_binary raises

ibf_load_code will leak memory allocated for the code if an exception is
raised. The following script reproduces the leak:

    bin = RubyVM::InstructionSequence.of(1.method(:abs)).to_binary

    10.times do
      100_000.times do
        RubyVM::InstructionSequence.load_from_binary(bin)
      rescue ArgumentError
      end
      puts `ps -o rss= -p #{$$}`
    end

Before:

    18004
    23380
    28756
    34260
    39892
    45396
    50772
    55892
    61012
    66132

After:

    12536
    12920
    13304
    13688
    14072
    14456
    14840
    15352
    15608
    15864

Author: peterzhu2118

compile.c

@@ -12926,6 +12926,9 @@ ibf_load_code(const struct ibf_load *load, rb_iseq_t *iseq, ibf_offset_t bytecod
     struct rb_call_data *cd_entries = load_body->call_data;
     int ic_index = 0;
 
+    load_body->iseq_encoded = code;
+    load_body->iseq_size = 0;
+
     iseq_bits_t * mark_offset_bits;
 
     iseq_bits_t tmp[1] = {0};
@@ -13057,7 +13060,6 @@ ibf_load_code(const struct ibf_load *load, rb_iseq_t *iseq, ibf_offset_t bytecod
         }
     }
 
-    load_body->iseq_encoded = code;
     load_body->iseq_size = code_index;
 
     if (ISEQ_MBITS_BUFLEN(load_body->iseq_size) == 1) {