build: replace usages of egrep with grep -E (#166)

egrep and fgrep have been deprecated for a long time in GNU grep, and as
of release 3.8 using them prints a warning message, as stated in the 3.8
release notes:

> The egrep and fgrep commands, which have been deprecated since
> release 2.5.3 (2007), now warn that they are obsolescent and should
> be replaced by grep -E and grep -F.

egrep is used during the build to query the version, and with the warning
that's now being printed this adds unneeded noise to the output of the
build. Replace the usage of egrep with grep -E to get rid of the warning.

Makefile

@@ -800,9 +800,9 @@ TOOLS_LIBRARY=$(STATIC_TOOLS_LIBRARY)
 endif
 STRESS_LIBRARY=$(STATIC_STRESS_LIBRARY)
 
-ROCKSDB_MAJOR = $(shell egrep "ROCKSDB_MAJOR.[0-9]" include/rocksdb/version.h | cut -d ' ' -f 3)
-ROCKSDB_MINOR = $(shell egrep "ROCKSDB_MINOR.[0-9]" include/rocksdb/version.h | cut -d ' ' -f 3)
-ROCKSDB_PATCH = $(shell egrep "ROCKSDB_PATCH.[0-9]" include/rocksdb/version.h | cut -d ' ' -f 3)
+ROCKSDB_MAJOR = $(shell grep -E "ROCKSDB_MAJOR.[0-9]" include/rocksdb/version.h | cut -d ' ' -f 3)
+ROCKSDB_MINOR = $(shell grep -E "ROCKSDB_MINOR.[0-9]" include/rocksdb/version.h | cut -d ' ' -f 3)
+ROCKSDB_PATCH = $(shell grep -E "ROCKSDB_PATCH.[0-9]" include/rocksdb/version.h | cut -d ' ' -f 3)
 
 # If NO_UPDATE_BUILD_VERSION is set we don't update util/build_version.cc, but
 # the file needs to already exist or else the build will fail

java/Makefile

@@ -96,9 +96,9 @@ NATIVE_JAVA_TEST_CLASSES = \
     org.rocksdb.WriteBatchTest\
     org.rocksdb.WriteBatchTestInternalHelper
 
-ROCKSDB_MAJOR = $(shell egrep "ROCKSDB_MAJOR.[0-9]" ../include/rocksdb/version.h | cut -d ' ' -f 3)
-ROCKSDB_MINOR = $(shell egrep "ROCKSDB_MINOR.[0-9]" ../include/rocksdb/version.h | cut -d ' ' -f 3)
-ROCKSDB_PATCH = $(shell egrep "ROCKSDB_PATCH.[0-9]" ../include/rocksdb/version.h | cut -d ' ' -f 3)
+ROCKSDB_MAJOR = $(shell grep -E "ROCKSDB_MAJOR.[0-9]" ../include/rocksdb/version.h | cut -d ' ' -f 3)
+ROCKSDB_MINOR = $(shell grep -E "ROCKSDB_MINOR.[0-9]" ../include/rocksdb/version.h | cut -d ' ' -f 3)
+ROCKSDB_PATCH = $(shell grep -E "ROCKSDB_PATCH.[0-9]" ../include/rocksdb/version.h | cut -d ' ' -f 3)
 
 NATIVE_INCLUDE = ./include
 ARCH := $(shell getconf LONG_BIT)