More sed tweaks to Makefile for portability.

The -E flag to specify extended regular expressions apparently is
not portable to all platforms, such as CentOS 4.5. Use an uglier
but hopefully more portable basic regular expression in Makefiles.

regress/Makefile

@@ -10,7 +10,7 @@ PG_CONFIG ?= pg_config
 
 # version as a number, e.g. 9.1.4 -> 901
 VERSION := $(shell $(PG_CONFIG) --version | awk '{print $$2}')
-INTVERSION := $(shell echo $$(($$(echo $(VERSION) | sed -E 's/([0-9]+)\.([0-9]+).*/\1*100+\2/'))))
+INTVERSION := $(shell echo $$(($$(echo $(VERSION) | sed 's/\([[:digit:]]\{1,\}\)\.\([[:digit:]]\{1,\}\).*/\1*100+\2/' ))))
 
 
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