Move visibility and "musttail" annotation checks to the RTS configure

All of this should boil down to `AC_DEFINE` not `AC_SUBST`, so it
belongs in the RTS configure and should be safe to move without
modification.

Progress towards #17191

configure.ac

@@ -1005,10 +1005,6 @@ else
    AC_SUBST([CabalLeadingUnderscore],[False])
 fi
 
-FP_VISIBILITY_HIDDEN
-
-FP_MUSTTAIL
-
 dnl ** check for librt
 AC_CHECK_LIB([rt], [clock_gettime], UseLibrt=YES, UseLibrt=NO)
 AC_SUBST([UseLibrt])

rts/configure.ac

@@ -33,6 +33,10 @@ GHC_CONVERT_PLATFORM_PARTS([host], [Host])
 FPTOOLS_SET_PLATFORM_VARS([host], [Host])
 FPTOOLS_SET_HASKELL_PLATFORM_VARS([Host])
 
+FP_VISIBILITY_HIDDEN
+
+FP_MUSTTAIL
+
 dnl ** check for librt
 AC_CHECK_FUNCS(clock_gettime timer_settime)
 FP_CHECK_TIMER_CREATE