AmigaOS4: Adapt configure to latest SDK. Restore grep workaround.

This reverts part of 54ddd00 to restore
a workaround for breakage in AmigaOS4 grep.

Makefile.common

@@ -153,7 +153,8 @@ endif
 # Get the current version information
 ######################################################################
 
-VERSION = $(shell grep SCUMMVM_VERSION "${srcdir}/base/internal_version.h" | cut -d\" -f2)
+# AmigaOS4's grep has a problem with "./" in pathnames, so use cat piped into grep.
+VERSION = $(shell cat "${srcdir}/base/internal_version.h" | grep SCUMMVM_VERSION | cut -d\" -f2)
 VER_MAJOR = $(shell echo $(VERSION) | cut -d. -f 1)
 VER_MINOR = $(shell echo $(VERSION) | cut -d. -f 2)
 VER_PATCH = $(shell echo $(VERSION) | cut -d. -f 3 | cut -c1)