[x86/Linux] Fix pow of tryrun (#11099)

x86/Linux has compatible math pow()
This will fix CoreFX System.Tests.MathFTests.Pow() failures

Author: seanshpark

cross/x86/tryrun.cmake

@@ -55,7 +55,7 @@ SET( HAVE_COMPATIBLE_ASIN_EXITCODE
      CACHE STRING "Result from TRY_RUN" FORCE)
 
 SET( HAVE_COMPATIBLE_POW_EXITCODE
-     1
+     0
      CACHE STRING "Result from TRY_RUN" FORCE)
 
 SET( HAVE_VALID_NEGATIVE_INF_POW_EXITCODE