Removes the assumption that CLK_TCK is a constant (#7519)

(which is not true on QNXNTO).

Submitted by: Stephen Paul Weber <singpolyma@singpolyma.net>

libraries/base/System/CPUTime.hsc

@@ -39,14 +39,6 @@ import CPUTime ( getCPUTime, cpuTimePrecision )
 #ifdef __GLASGOW_HASKELL__
 import Foreign.Safe
 import Foreign.C
-#if !defined(CLK_TCK)
-import System.IO.Unsafe (unsafePerformIO)
-#endif
-
--- For _SC_CLK_TCK
-#if HAVE_UNISTD_H
-#include <unistd.h>
-#endif
 
 -- For struct rusage
 #if !defined(mingw32_HOST_OS) && !defined(irix_HOST_OS)
@@ -60,11 +52,6 @@ import System.IO.Unsafe (unsafePerformIO)
 #include <windows.h>
 #endif
 
--- for CLK_TCK
-#if HAVE_TIME_H
-#include <time.h>
-#endif
-
 -- for struct tms
 #if HAVE_SYS_TIMES_H
 #include <sys/times.h>
@@ -185,13 +172,8 @@ cpuTimePrecision = round ((1000000000000::Integer) % fromIntegral (clockTicks))
 #endif
 
 #ifdef __GLASGOW_HASKELL__
+foreign import ccall unsafe clk_tck :: CLong
+
 clockTicks :: Int
-clockTicks =
-#if defined(CLK_TCK)
-    (#const CLK_TCK)
-#else
-    unsafePerformIO (sysconf (#const _SC_CLK_TCK) >>= return . fromIntegral)
-foreign import ccall unsafe sysconf :: CInt -> IO CLong
-#endif
+clockTicks = fromIntegral clk_tck
 #endif /* __GLASGOW_HASKELL__ */
-

libraries/base/base.cabal

@@ -225,6 +225,7 @@ Library {
         cbits/inputReady.c
         cbits/primFloat.c
         cbits/md5.c
+        cbits/sysconf.c
     include-dirs: include
     includes:    HsBase.h
     install-includes:    HsBase.h HsBaseConfig.h EventConfig.h WCsubst.h consUtils.h Typeable.h

libraries/base/cbits/sysconf.c

+#include "HsBaseConfig.h"
+
+/* For _SC_CLK_TCK */
+#if HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+/* for CLK_TCK */
+#if HAVE_TIME_H
+#include <time.h>
+#endif
+
+long clk_tck(void) {
+#if defined(CLK_TCK)
+    return (CLK_TCK);
+#else
+    return sysconf(_SC_CLK_TCK);
+#endif
+}