Add !!( ) to branch predictor hints to force 1 or 0 result

This makes it so we can program as usual and no issues result from
for example:
if (MVM_LIKELY(my_var))
Turns into __builtin_expect(myvar, 1). But in most cases my_var isn't 1
even though it evaluates as true.
Make we instead turn it into __builtin_expect(!!myvar, 1) which will be
correct in all cases where myvar is not zero.

The compiler may have been smart enough to figure this out before or
it may not have been, but this resolves warnings of type issues when
using a pointer in a conditional and we can be more sure that MVM_LIKELY
is operating properly.

build/setup.pm

@@ -287,9 +287,9 @@ our %COMPILERS = (
         noreturnspecifier => '',
         noreturnattribute => '__attribute__((noreturn))',
         formatattribute   => '__attribute__((format(X, Y, Z)))',
-        expect_likely => '__builtin_expect((condition), 1)',
-        expect_unlikely => '__builtin_expect((condition), 0)',
-        expect_condition => '__builtin_expect((condition), (expection))'
+        expect_likely => '__builtin_expect(!!(condition), 1)',
+        expect_unlikely => '__builtin_expect(!!(condition), 0)',
+        expect_condition => '__builtin_expect(!!(condition), (expection))'
     },
 
     clang => {
@@ -315,9 +315,9 @@ our %COMPILERS = (
         noreturnattribute => '__attribute__((noreturn))',
         formatattribute   => '__attribute__((format(X, Y, Z)))',
         vectorizerspecifier => '_Pragma ("clang loop vectorize(enable)")',
-        expect_likely => '__builtin_expect((condition), 1)',
-        expect_unlikely => '__builtin_expect((condition), 0)',
-        expect_condition => '__builtin_expect((condition), (expection))'
+        expect_likely => '__builtin_expect(!!(condition), 1)',
+        expect_unlikely => '__builtin_expect(!!(condition), 0)',
+        expect_condition => '__builtin_expect(!!(condition), (expection))'
     },
 
     cl => {