With the Oracle Developer Studio 12.6 compiler, #line directives alter
the current source file location for purposes of #include "..."
directives. Hence, a VPATH build failed with 'cannot find include file:
"specscanner.c"'. With two exceptions, parser-containing directories
already add "-I. -I$(srcdir)"; eliminate the exceptions. Back-patch to
9.6 (all supported versions).
top_builddir = ../../..
include $(top_builddir)/src/Makefile.global
-override CPPFLAGS := -I$(srcdir) -I$(libpq_srcdir) -I$(srcdir)/../regress $(CPPFLAGS)
+override CPPFLAGS := -I. -I$(srcdir) -I$(libpq_srcdir) \
+ -I$(srcdir)/../regress $(CPPFLAGS)
OBJS = specparse.o isolationtester.o $(WIN32RES)