Minor optimisations and bug fixes

Fix bug in mt_mpmc.c, in Linux mutexes are not recursive.
Add arena_trim_string() to the arena API
Removing arena->path, now paths are pushed to arena->metadata
Replacing fe->owner[128] with char *owner; the owner is not pushed as a
string to arena->metadata and trimed with arena_trim_string()
Improving cache locality in arena->metadata, the memory layout is not
fe; fe->path; fe->owner.
Cache aligning all arenas except HasherContext->arena to sizeof(void *).
Pushing elements one by one instead of snprintf() in finalize_file() and
hash_worker().
Getting the full path of current directory instead of "."
Fixing bug in path formating, this allow us to remove normalize_path()
from the hot loop.

arena.c

@@ -196,7 +196,7 @@ mem_arena *arena_create(arena_params *params) { // mk create
       arena->free_list = arena_create(&(arena_params){
           .reserve_size = MiB(1),
           .commit_size = MiB(1),
-          .align = ARENA_ALIGN,
+          .align = ARENA_CACHE_ALIGN,
           .push_size = sizeof(arena_free_node),
           .allow_free_list = false,
           .free_list = NULL,
@@ -620,6 +620,119 @@ void *arena_swapback_pop(mem_arena **arena_ptr, u64 index) { // mk swapback
 /* ============================================================
    Utilities
    ============================================================ */
+typedef enum arena_trim_flags {
+  ARENA_TRIM_NONE = 0,
+
+  ARENA_TRIM_SPACE = 1 << 0,
+  ARENA_TRIM_TAB = 1 << 1,
+  ARENA_TRIM_LF = 1 << 2,
+  ARENA_TRIM_CR = 1 << 3,
+  ARENA_TRIM_NUL = 1 << 4,
+
+} arena_trim_flags;
+
+u64 arena_trim_string(mem_arena **arena_ptr, char *str, u8 termination_flags) {
+  ASSERT(arena_ptr);
+  ASSERT(*arena_ptr);
+  ASSERT(str);
+
+  if (!arena_ptr || !*arena_ptr || !str) {
+    return 0;
+  }
+
+  mem_arena *arena = *arena_ptr;
+
+  /* ------------------------------------------------------------
+     Find owning block
+     ------------------------------------------------------------ */
+
+  mem_arena *owner = arena_block_from_ptr(arena, (u8 *)str);
+
+  ASSERT(owner);
+  if (!owner) {
+    return 0;
+  }
+
+  /* ------------------------------------------------------------
+     Must be current block
+     ------------------------------------------------------------ */
+
+  if (owner != arena) {
+    fprintf(stderr, "arena_trim_string(): string is not "
+                    "in current arena block.\n");
+    return 0;
+  }
+
+  /* ------------------------------------------------------------
+     Compute string position
+     ------------------------------------------------------------ */
+
+  u64 str_pos = arena_pos_from_ptr(arena, str);
+
+  /* ------------------------------------------------------------
+     Original reserved size
+     ------------------------------------------------------------ */
+
+  u64 allocated_size = arena->pos - str_pos;
+
+  /* ------------------------------------------------------------
+     Compute sizes
+     ------------------------------------------------------------ */
+
+  u64 str_size = strlen(str);
+
+  char *dst = str + str_size;
+  u64 termination_size = 0;
+
+  if (termination_flags & ARENA_TRIM_SPACE) {
+    *dst++ = ' ';
+    termination_size++;
+  }
+
+  if (termination_flags & ARENA_TRIM_TAB) {
+    *dst++ = '\t';
+    termination_size++;
+  }
+
+  if (termination_flags & ARENA_TRIM_CR) {
+    *dst++ = '\r';
+    termination_size++;
+  }
+
+  if (termination_flags & ARENA_TRIM_LF) {
+    *dst++ = '\n';
+    termination_size++;
+  }
+
+  if (termination_flags & ARENA_TRIM_NUL) {
+    *dst++ = '\0';
+    termination_size++;
+  }
+  /* ------------------------------------------------------------
+     Final used size
+     ------------------------------------------------------------ */
+
+  u64 used_size = str_size + termination_size;
+
+  used_size = ALIGN_UP_POW2(used_size, arena->align);
+
+  /* ------------------------------------------------------------
+     Overflow detection
+     ------------------------------------------------------------ */
+
+  if (used_size > allocated_size) {
+    fprintf(stderr, "arena_trim_string(): string overflow "
+                    "detected.\n");
+  }
+
+  /* ------------------------------------------------------------
+     Update arena position
+     ------------------------------------------------------------ */
+
+  arena->pos = str_pos + used_size;
+
+  return used_size;
+}
 
 void *arena_clear(mem_arena **arena_ptr) { // mk clear
 
@@ -801,7 +914,7 @@ mem_arena_temp arena_scratch_get(mem_arena **conflicts, u32 num_conflicts) {
     arena_params params = {
         .reserve_size = MiB(64),
         .commit_size = MiB(1),
-        .align = ARENA_ALIGN,
+        .align = ARENA_CACHE_ALIGN,
         .push_size = 8,
         .allow_free_list = false,
         .allow_swapback = true,