change underlying type of clock_t to be uniform and match ABI

previously we were using an unsigned type on 32-bit systems so that
subtraction would be well-defined when it wrapped, but since wrapping
is non-conforming anyway (when clock() overflows, it has to return -1)
the only use of unsigned would be to buy a little bit more time before
overflow. this does not seem worth having the type vary per-arch
(which leads to more arch-specific bugs) or disagree with the ABI musl
(mostly) follows.

arch/arm/bits/alltypes.h.sh

@@ -104,7 +104,7 @@ TYPEDEF unsigned long long fsfilcnt_t;
 
 TYPEDEF void * timer_t;
 TYPEDEF int clockid_t;
-TYPEDEF unsigned long clock_t;
+TYPEDEF long clock_t;
 
 TYPEDEF struct { unsigned long __bits[128/sizeof(long)]; } sigset_t;
 TYPEDEF struct __siginfo siginfo_t;

arch/i386/bits/alltypes.h.sh

@@ -117,7 +117,7 @@ TYPEDEF unsigned long long fsfilcnt_t;
 
 TYPEDEF void * timer_t;
 TYPEDEF int clockid_t;
-TYPEDEF unsigned long clock_t;
+TYPEDEF long clock_t;
 
 TYPEDEF struct { unsigned long __bits[128/sizeof(long)]; } sigset_t;
 TYPEDEF struct __siginfo siginfo_t;

arch/microblaze/bits/alltypes.h.sh

@@ -104,7 +104,7 @@ TYPEDEF unsigned long long fsfilcnt_t;
 
 TYPEDEF void * timer_t;
 TYPEDEF int clockid_t;
-TYPEDEF unsigned long clock_t;
+TYPEDEF long clock_t;
 
 TYPEDEF struct { unsigned long __bits[128/sizeof(long)]; } sigset_t;
 TYPEDEF struct __siginfo siginfo_t;

arch/mips/bits/alltypes.h.sh

@@ -104,7 +104,7 @@ TYPEDEF unsigned long long fsfilcnt_t;
 
 TYPEDEF void * timer_t;
 TYPEDEF int clockid_t;
-TYPEDEF unsigned long clock_t;
+TYPEDEF long clock_t;
 
 TYPEDEF struct { unsigned long __bits[128/sizeof(long)]; } sigset_t;
 TYPEDEF struct __siginfo siginfo_t;

arch/powerpc/bits/alltypes.h.sh

@@ -104,7 +104,7 @@ TYPEDEF unsigned long long fsfilcnt_t;
 
 TYPEDEF void * timer_t;
 TYPEDEF int clockid_t;
-TYPEDEF unsigned long clock_t;
+TYPEDEF long clock_t;
 
 TYPEDEF struct { unsigned long __bits[128/sizeof(long)]; } sigset_t;
 TYPEDEF struct __siginfo siginfo_t;