Revert "Make sdl2-config interpreter configurable"

This reverts commit b9f005505b.

Making the interpreter configurable is a band-aid fix.
So revert the workaround until we know the actual cause.

configure.ac

@@ -113,18 +113,6 @@ esac
 AC_SUBST(LINKER)
 AC_SUBST(LIBTOOLLINKERTAG)
 
-case "$host" in
-    # On Solaris, jack must be linked deferred explicitly
-    # to prevent undefined symbol failures.
-    *-*-solaris*)
-        SDL2_CONFIG_INTERPRETER=/bin/bash
-        ;;
-    *)
-        SDL2_CONFIG_INTERPRETER=/bin/sh
-        ;;
-esac
-AC_SUBST(SDL2_CONFIG_INTERPRETER)
-
 if test x$srcdir != x.; then
     INCLUDE="-Iinclude $INCLUDE"
 elif test -d .git; then