ANDROID: 16K: Add VMA padding size to smaps output

Instead of printing ?? for unexpected vm_flags due to
vm padding flag bits; print the size of the padding in kB if any.

Example output:

7ff6306c2000-7ff6306c3000 r--p 00000000 fe:09 1912                       /system/lib64/bootstrap/libdl.so
Size:                  4 kB
KernelPageSize:        4 kB
MMUPageSize:           4 kB
Rss:                   4 kB
Pss:                   0 kB
Pss_Dirty:             0 kB
Shared_Clean:          4 kB
Shared_Dirty:          0 kB
Private_Clean:         0 kB
Private_Dirty:         0 kB
Referenced:            4 kB
Anonymous:             0 kB
KSM:                   0 kB
LazyFree:              0 kB
AnonHugePages:         0 kB
ShmemPmdMapped:        0 kB
FilePmdMapped:         0 kB
Shared_Hugetlb:        0 kB
Private_Hugetlb:       0 kB
Swap:                  0 kB
SwapPss:               0 kB
Locked:                0 kB
THPeligible:           0
VmFlags: rd mr mw me pad=12kB    // <========
7ff6306c3000-7ff6306c6000 ---p 00000000 00:00 0                          [page size compat]
Size:                 12 kB      // <========
KernelPageSize:        4 kB
MMUPageSize:           4 kB
Rss:                   0 kB
Pss:                   0 kB
Pss_Dirty:             0 kB
Shared_Clean:          0 kB
Shared_Dirty:          0 kB
Private_Clean:         0 kB
Private_Dirty:         0 kB
Referenced:            0 kB
Anonymous:             0 kB
KSM:                   0 kB
LazyFree:              0 kB
AnonHugePages:         0 kB
ShmemPmdMapped:        0 kB
FilePmdMapped:         0 kB
Shared_Hugetlb:        0 kB
Private_Hugetlb:       0 kB
Swap:                  0 kB
SwapPss:               0 kB
Locked:                0 kB
THPeligible:           0
VmFlags: mr mw me

Bug: 409239984
Bug: 404710273
Bug: 394468578
Change-Id: I4e996f207c9eb980d1a108418c506542722e7265
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>