Fold conv package into fmt

Both packages had nearly identical dependency requirements, so merging
them should help reduce the complexity of the build graph.

libc/calls/hefty/fork-nt.c

@@ -22,7 +22,7 @@
 #include "libc/calls/hefty/ntspawn.h"
 #include "libc/calls/hefty/spawn.h"
 #include "libc/calls/internal.h"
-#include "libc/conv/itoa.h"
+#include "libc/fmt/itoa.h"
 #include "libc/nt/enum/filemapflags.h"
 #include "libc/nt/enum/pageflags.h"
 #include "libc/nt/enum/startf.h"

libc/calls/hefty/hefty.mk

@@ -37,7 +37,6 @@ LIBC_CALLS_HEFTY_A_CHECKS =				\
 LIBC_CALLS_HEFTY_A_DIRECTDEPS =				\
 	LIBC_ALG					\
 	LIBC_CALLS					\
-	LIBC_CONV					\
 	LIBC_FMT					\
 	LIBC_MEM					\
 	LIBC_NEXGEN32E					\

libc/calls/hefty/mkntcmdline.c

@@ -20,7 +20,7 @@
 #include "libc/alg/arraylist2.internal.h"
 #include "libc/calls/calls.h"
 #include "libc/calls/hefty/ntspawn.h"
-#include "libc/conv/conv.h"
+#include "libc/fmt/conv.h"
 #include "libc/macros.h"
 #include "libc/mem/mem.h"
 #include "libc/nexgen32e/hascharacter.internal.h"

libc/calls/hefty/mkntenvblock.c

@@ -19,7 +19,7 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #include "libc/alg/arraylist2.internal.h"
 #include "libc/calls/hefty/ntspawn.h"
-#include "libc/conv/conv.h"
+#include "libc/fmt/conv.h"
 #include "libc/macros.h"
 #include "libc/mem/mem.h"
 #include "libc/str/oldutf16.internal.h"

libc/calls/hefty/ntspawn.c

@@ -24,7 +24,7 @@
 #include "libc/calls/calls.h"
 #include "libc/calls/hefty/ntspawn.h"
 #include "libc/calls/internal.h"
-#include "libc/conv/conv.h"
+#include "libc/fmt/conv.h"
 #include "libc/nt/enum/processcreationflags.h"
 #include "libc/nt/process.h"
 #include "libc/nt/runtime.h"

libc/calls/hefty/spawnve-sysv.c

@@ -22,8 +22,8 @@
 #include "libc/calls/hefty/internal.h"
 #include "libc/calls/hefty/spawn.h"
 #include "libc/calls/internal.h"
-#include "libc/conv/conv.h"
 #include "libc/dce.h"
+#include "libc/fmt/conv.h"
 #include "libc/mem/mem.h"
 #include "libc/paths.h"
 #include "libc/runtime/runtime.h"