Description:
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Math constants M_SQRTPI, M_SQRT3, M_LNPI and M_EULER introduced in version 4.0.2 are not defined anymore in version 5.1.0b3.

Reproduce code:
---------------
echo 'M_SQRTPI=' . M_SQRTPI . '<br />' . "\n";
echo 'M_SQRT3=' . M_SQRT3 . '<br />' . "\n";
echo 'M_LNPI=' . M_LNPI . '<br />' . "\n";
echo 'M_EULER=' . M_EULER . '<br />' . "\n";


Expected result:
----------------
M_SQRTPI=1.7724538509055
M_SQRT3=1.7320508075689
M_LNPI=1.1447298858494
M_EULER=0.57721566490153

Actual result:
--------------
Notice: Use of undefined constant M_SQRTPI - assumed 'M_SQRTPI' in c:\Inetpub\wwwroot\php\math.php on line 23
M_SQRTPI=M_SQRTPI

Notice: Use of undefined constant M_SQRT3 - assumed 'M_SQRT3' in c:\Inetpub\wwwroot\php\math.php on line 24
M_SQRT3=M_SQRT3

Notice: Use of undefined constant M_LNPI - assumed 'M_LNPI' in c:\Inetpub\wwwroot\php\math.php on line 25
M_LNPI=M_LNPI

Notice: Use of undefined constant M_EULER - assumed 'M_EULER' in c:\Inetpub\wwwroot\php\math.php on line 26
M_EULER=M_EULER