asm: make all text section labels .L local

To help with backtraces if we ever fix them due to the lkmc_asm_main_after_prologue debacle.

userland/arch/x86_64/jmp.S

@@ -6,7 +6,7 @@
 #include <lkmc.h>
 
 LKMC_PROLOGUE
-    jmp after_fail
+    jmp .Lafter_fail
     LKMC_ASSERT_FAIL
-after_fail:
+.Lafter_fail:
 LKMC_EPILOGUE

userland/arch/x86_64/jmp_indirect.S

@@ -8,15 +8,15 @@
 LKMC_PROLOGUE
     /* Address in memory. */
 .section .rodata
-    label_address: .quad memory_label
+    label_address: .quad .Lmemory_label
 .text
     jmp *label_address
     LKMC_ASSERT_FAIL
-memory_label:
+.Lmemory_label:
 
     /* Address in register. */
-    lea register_label(%rip), %rax
+    lea .Lregister_label(%rip), %rax
     jmp *%rax
     LKMC_ASSERT_FAIL
-register_label:
+.Lregister_label:
 LKMC_EPILOGUE

userland/arch/x86_64/loop.S

@@ -13,9 +13,9 @@ LKMC_PROLOGUE
      */
     mov $0, %rax
     mov $3, %rcx
-loop_label:
+.Lloop_label:
     inc %rax
-    loop loop_label
+    loop .Lloop_label
     LKMC_ASSERT_EQ(%rax, $3)
 
     /* LOOPE
@@ -37,10 +37,10 @@ loop_label:
     /* Array length. */
     mov $4, %rcx
     mov $-1, %rax
-loope_label:
+.Lloope_label:
     inc %rax
     cmpb $0, loope_array(%rax)
-    loope loope_label
+    loope .Lloope_label
     /* The first non-zero item (1) was at index 2. */
     LKMC_ASSERT_EQ(%rax, $2)