[libc][config] Add malloc as baremetal arm entrypoint

Author: PiJoules

libc/config/baremetal/arm/entrypoints.txt

@@ -173,6 +173,7 @@ set(TARGET_LIBC_ENTRYPOINTS
     libc.src.stdlib.ldiv
     libc.src.stdlib.llabs
     libc.src.stdlib.lldiv
+    libc.src.stdlib.malloc
     libc.src.stdlib.qsort
     libc.src.stdlib.rand
     libc.src.stdlib.srand