Missing some instrumentations when instrumenting binary with AFL

RetroWrite generates labels with the format as `.L%x` in
https://github.com/HexHive/retrowrite/blob/243db5811b96dfe07e6c697b3a2e2d61e0e7855b/librw/rw.py#L190
and
https://github.com/HexHive/retrowrite/blob/9e2e633e9ab165681733f3255e648a62b22e6368/librw/container.py#L191

However, for the `afl-gcc` compilers of AFL-family fuzzers such as [AFL++](https://github.com/AFLplusplus/AFLplusplus), they only instrument the label start with `.L%d`

https://github.com/AFLplusplus/AFLplusplus/blob/32a0d6ac31554a47dca591f8978982758fb87677/src/afl-as.c#L464-L466
```C
if ((isdigit(line[2]) ||
(clang_mode && !strncmp(line + 1, "LBB", 3))) &&
R(100) < (long)inst_ratio) {
```

Taking the nm in binutils as an example, the `.L9ffea` basic block is instrumented while `.La0047` and `.La0058` are not instrumented.
After the fix, the number of instrumentation increase from 39511 to 47795.
```
.L9ffea:
.LC9ffea:

/* --- AFL TRAMPOLINE (64-BIT) --- */

.align 4

leaq -(128+24)(%rsp), %rsp
movq %rdx, 0(%rsp)
movq %rcx, 8(%rsp)
movq %rax, 16(%rsp)
movq $0x00006e12, %rcx
call __afl_maybe_log
movq 16(%rsp), %rax
movq 8(%rsp), %rcx
movq 0(%rsp), %rdx
leaq (128+24)(%rsp), %rsp

/* --- END --- */

movq -0x48(%rbp), %rax
.LC9ffee:
movq -0x58(%rbp), %rcx
.LC9fff2:
movq %rax, 8(%rcx)
.LC9fff6:
movq -0x58(%rbp), %rax
.LC9fffa:
movl $0xffffffff, 0x60(%rax)
.LCa0001:
movq -0x58(%rbp), %rax
.LCa0005:
movl $1, 0x64(%rax)
.LCa000c:
movl $1, -0x64(%rbp)
.LCa0013:
movq -0x20(%rbp), %rax
.LCa0017:
movq (%rax), %rax
.LCa001a:
cmpq $0, 0x100(%rax)
.LCa0022:
je .La0047

/* --- AFL TRAMPOLINE (64-BIT) --- */

.align 4

leaq -(128+24)(%rsp), %rsp
movq %rdx, 0(%rsp)
movq %rcx, 8(%rsp)
movq %rax, 16(%rsp)
movq $0x0000740b, %rcx
call __afl_maybe_log
movq 16(%rsp), %rax
movq 8(%rsp), %rcx
movq 0(%rsp), %rdx
leaq (128+24)(%rsp), %rsp

/* --- END --- */

.LCa0028:
movq -0x20(%rbp), %rax
.LCa002c:
movq (%rax), %rax
.LCa002f:
movq 0x100(%rax), %rax
.LCa0036:
cmpl $0, 0x10(%rax)
.LCa003a:
jne .La0047

/* --- AFL TRAMPOLINE (64-BIT) --- */

.align 4

leaq -(128+24)(%rsp), %rsp
movq %rdx, 0(%rsp)
movq %rcx, 8(%rsp)
movq %rax, 16(%rsp)
movq $0x000050f3, %rcx
call __afl_maybe_log
movq 16(%rsp), %rax
movq 8(%rsp), %rcx
movq 0(%rsp), %rdx
leaq (128+24)(%rsp), %rsp

/* --- END --- */

.LCa0040:
movl $0, -0x64(%rbp)
.La0047:
.LCa0047:
movq -0x20(%rbp), %rax
.LCa004b:
movq (%rax), %rax
.LCa004e:
addq $0x100, %rax
.LCa0054:
movq %rax, -0x60(%rbp)
.La0058:
.LCa0058:
movq -0x60(%rbp), %rax
.LCa005c:
cmpq $0, (%rax)
.LCa0060:
je .La007f
```

I think RetroWrite could output the label with format `.L%d` (see https://github.com/HexHive/retrowrite/pull/27), or modify the code in `afl-as.c` to
```C
if (((isdigit(line[2]) || (line[2] >= 'a' && line[2] <= 'f')) ||
(clang_mode && !strncmp(line + 1, "LBB", 3))) &&
R(100) < (long)inst_ratio) {
```

The assembly code files are attached [here](https://github.com/HexHive/retrowrite/files/7006397/nm_asm.tar.gz).

Start with the label generation in librw/rw.py around line 190 and librw/container.py around line 191, then compare it with AFL's label handling in afl-as.c. Use the attached nm assembly to reproduce the missed instrumentation and verify that labels such as .La0047 and .La0058 are handled. Done means the affected labels are instrumented without regressing existing AFL instrumentation.

Written by the indexing model from the issue text.