I've installed Oracle 11.2 XE and downloaded the Qt libraries 5.0 Beta 2 sources.
Configured with:
./configure -plugin-sql-mysql -plugin-sql-oci -system-sqlite -prefix /home/mwaack
Configure worked, no problems.
Building the sources failed:

g++ -c -m64 -pipe -O2 -std=c+0x -fvisibility=hidden -fvisibility-inlines-hidden -fno-exceptions -Wall -W -D_REENTRANT -fPIC -DQT_NO_CAST_TO_ASCII -DQT_NO_CAST_FROM_ASCII -DQT_NO_EXCEPTIONS -D_LARGEFILE64_SOURCE -D_LARGEFILE_SOURCE -DQT_NO_DEBUG -DQT_PLUGIN -DQT_SQL_LIB -DQT_CORE_LIB -I../../../../mkspecs/linux-g+-64 -I. -I/u01/app/oracle/product/11.2.0/xe/rdbms/public -I../../../../include -I../../../../include/QtSql -I../../../../include/QtSql/5.0.0 -I../../../../include/QtSql/5.0.0/QtSql -I../../../../include/QtCore -I.moc/release-shared -o .obj/release-shared/qsql_oci.o ../../../sql/drivers/oci/qsql_oci.cpp
../../../sql/drivers/oci/qsql_oci.cpp: In member function ‘virtual bool QOCIResult::execBatch(bool)’:
../../../sql/drivers/oci/qsql_oci.cpp:2043:8: error: ‘struct QOCIResultPrivate’ has no member named ‘resetBindCount’
../../../sql/drivers/oci/qsql_oci.cpp:2044:15: error: ‘struct QOCIResultPrivate’ has no member named ‘error’
In file included from ../../../../include/QtCore/qmetatype.h:1:0,
from ../../../../include/QtCore/../../src/corelib/kernel/qvariant.h:48,
from ../../../../include/QtCore/qvariant.h:1,
from ../../../../include/QtSql/../../src/sql/kernel/qsqlresult.h:45,
from ../../../../include/QtSql/qsqlresult.h:1,
from ../../../sql/drivers/oci/qsql_oci.h:45,
from ../../../sql/drivers/oci/qsql_oci.cpp:42:
../../../../include/QtCore/../../src/corelib/kernel/qmetatype.h: At global scope:
../../../../include/QtCore/../../src/corelib/kernel/qmetatype.h: In instantiation of ‘QtPrivate::IsPointerToTypeDerivedFromQObject<OCIEnv*>’:
../../../../include/QtCore/../../src/corelib/kernel/qmetatype.h:554:14: instantiated from ‘QtPrivate::QMetaTypeTypeFlags<OCIEnv*>’
../../../../include/QtCore/../../src/corelib/kernel/qmetatype.h:580:71: instantiated from ‘int qRegisterNormalizedMetaType(const QByteArray&, T*) [with T = OCIEnv*]’
../../../../include/QtCore/../../src/corelib/kernel/qmetatype.h:603:68: instantiated from ‘int qRegisterMetaType(const char*, T*) [with T = OCIEnv*]’
../../../sql/drivers/oci/qsql_oci.cpp:85:1: instantiated from here
../../../../include/QtCore/../../src/corelib/kernel/qmetatype.h:457:24: error: invalid application of ‘sizeof’ to incomplete type ‘OCIEnv’
../../../../include/QtCore/../../src/corelib/kernel/qmetatype.h: In instantiation of ‘QtPrivate::IsPointerToTypeDerivedFromQObject<OCIStmt*>’:
../../../../include/QtCore/../../src/corelib/kernel/qmetatype.h:554:14: instantiated from ‘QtPrivate::QMetaTypeTypeFlags<OCIStmt*>’
../../../../include/QtCore/../../src/corelib/kernel/qmetatype.h:580:71: instantiated from ‘int qRegisterNormalizedMetaType(const QByteArray&, T*) [with T = OCIStmt*]’
../../../../include/QtCore/../../src/corelib/kernel/qmetatype.h:603:68: instantiated from ‘int qRegisterMetaType(const char*, T*) [with T = OCIStmt*]’
../../../sql/drivers/oci/qsql_oci.cpp:86:1: instantiated from here
../../../../include/QtCore/../../src/corelib/kernel/qmetatype.h:457:24: error: invalid application of ‘sizeof’ to incomplete type ‘OCIStmt’
../../../sql/drivers/oci/qsql_oci.cpp: In member function ‘virtual bool QOCIResult::execBatch(bool)’:
../../../sql/drivers/oci/qsql_oci.cpp:2045:1: warning: control reaches end of non-void function [-Wreturn-type]
make[5]: *** [.obj/release-shared/qsql_oci.o] Error 1
make[5]: Leaving directory `/home/mwaack/qt-everywhere-opensource-src-5.0.0-beta2/qtbase/src/plugins/sqldrivers/oci'
make[4]: *** [sub-oci-make_first] Error 2
make[4]: Leaving directory `/home/mwaack/qt-everywhere-opensource-src-5.0.0-beta2/qtbase/src/plugins/sqldrivers'
make[3]: *** [sub-sqldrivers-make_first] Error 2
make[3]: Leaving directory `/home/mwaack/qt-everywhere-opensource-src-5.0.0-beta2/qtbase/src/plugins'
make[2]: *** [sub-plugins-make_first] Error 2
make[2]: Leaving directory `/home/mwaack/qt-everywhere-opensource-src-5.0.0-beta2/qtbase/src'
make[1]: *** [sub-src-make_first] Error 2
make[1]: Leaving directory `/home/mwaack/qt-everywhere-opensource-src-5.0.0-beta2/qtbase'
make: *** [module-qtbase-make_first] Error 2
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