Fix double free possibility in wolfSSL_X509_set_ext #3870

Job	Run time
make check (--enable-smallstackcache --enable-smallstack --enable-all --enable-debug-trace-errcod...	2m 55s
make check (--enable-amdrand --enable-smallstackcache --enable-smallstack --enable-all CFLAGS="-D...	3m 0s
make check (--enable-smallstack --enable-all CFLAGS="-DWC_RNG_SEED_CB -DWOLFSSL_TRACK_MEMORY -DW...	3m 4s
make check (--disable-asm --enable-wolfEntropy --enable-smallstackcache --enable-smallstack --ena...	4m 57s
make check (--enable-intelrdseed --enable-smallstackcache --enable-smallstack --enable-all CFLAGS...	2m 35s
make check (--enable-all --enable-debug-trace-errcodes CFLAGS="-DWC_RNG_SEED_CB -DWOLFSSL_TRACK_M...	2m 59s
make check (--enable-wolfEntropy --enable-smallstackcache --enable-smallstack --enable-all CFLAGS...	4m 15s
	23m 45s

Provide feedback