Canonicalize the path used by sh.

With a bunch of LibC work to support the feature. LibC now initializes
AK::StringImpl by default. It's now fine to use AK in LibC/Userland! :^)

Kernel/Makefile

@@ -59,7 +59,7 @@ FLAVOR_FLAGS = -mregparm=3 -march=i386 -m32 -fno-exceptions -fno-rtti -fmerge-al
 OPTIMIZATION_FLAGS = -Os -fno-asynchronous-unwind-tables
 INCLUDE_FLAGS = -I.. -I.
 
-DEFINES = -DSERENITY -DSANITIZE_PTRS
+DEFINES = -DSERENITY -DKERNEL -DSANITIZE_PTRS
 
 CXXFLAGS = $(WARNING_FLAGS) $(OPTIMIZATION_FLAGS) $(KERNEL_FLAGS) $(FLAVOR_FLAGS) $(ARCH_FLAGS) $(STANDARD_FLAGS) $(INCLUDE_FLAGS) $(DEFINES)
 #CXX = /usr/local/gcc-4.8.1-for-linux64/bin/x86_64-pc-linux-g++

Kernel/Task.cpp

@@ -142,6 +142,7 @@ Task::Region* Task::allocateRegion(size_t size, String&& name)
 
 bool Task::deallocateRegion(Region& region)
 {
+    InterruptDisabler disabler;
     for (size_t i = 0; i < m_regions.size(); ++i) {
         if (m_regions[i].ptr() == &region) {
             // FIXME: This seems racy.