i#3799: Fix leak and false trigger on DR reload (#3800)

Adds ignoring of kernels labeling DR's .bss as "[heap]", to avoid
unnecessary reloading at startup.

Fixes failures to unmap the executable's headers on a reload.

Fixes #3799

core/unix/loader.c

@@ -1629,6 +1629,8 @@ dynamorio_lib_gap_empty(void)
         while (memquery_iterator_next(&iter) && iter.vm_start < dr_end) {
             if (iter.vm_start >= dr_start && iter.vm_end <= dr_end &&
                 iter.comment[0] != '\0' &&
+                /* i#3799: ignore the kernel labeling DR's .bss as "[heap]". */
+                strcmp(iter.comment, "[heap]") != 0 &&
                 strcmp(iter.comment, dynamorio_library_path) != 0) {
                 /* There's a non-anon mapping inside: probably vvar and/or vdso. */
                 res = false;
@@ -1877,6 +1879,7 @@ privload_early_inject(void **sp, byte *old_libdr_base, size_t old_libdr_size)
     /* i#1227: on a conflict with the app (+ room for the brk): reload ourselves */
     if (get_dynamorio_dll_start() < exe_end + APP_BRK_GAP &&
         get_dynamorio_dll_end() > exe_map) {
+        elf_loader_destroy(&exe_ld);
         reload_dynamorio(sp, exe_map, exe_end + APP_BRK_GAP);
         ASSERT_NOT_REACHED();
     }
@@ -1887,6 +1890,7 @@ privload_early_inject(void **sp, byte *old_libdr_base, size_t old_libdr_size)
      * very often.
      */
     if (!dynamorio_lib_gap_empty()) {
+        elf_loader_destroy(&exe_ld);
         reload_dynamorio(sp, get_dynamorio_dll_start(), get_dynamorio_dll_end());
         ASSERT_NOT_REACHED();
     }